This page documents the Cymru machines we have and how to (re)install
them.

[[_TOC_]]

# How-to

## Creating a new machine

If you need to create a new machine (from metal) inside the cluster,
you should probably follow this procedure:

 1. Get access to the virtual console by:
    1. getting [Management network access](#management-network-access)
    2. get the nasty Java-based [Virtual console](#virtual-console) running
    3. [boot a rescue image][], typically grml
 2. [Bootstrap the installer](#bootstrapping-installer)
 3. Follow the [automated install procedure](#automated-install-procedure) - be careful to follow
    all the extra steps as the installer is not fully automated and
    still somewhat flaky

[boot a rescue image]: #booting-a-rescue-image

If you want to create a Ganeti **instance**, you should really just
follow the [Ganeti documentation](howto/ganeti) instead, as this page mostly
talks about Cymru- and metal-specific things.

## Bootstrapping installer

To get Debian installed, you need to bootstrap some Debian SSH server
to allow our installer to proceed. This must be done by loading a
[grml](https://grml.org) live image through the Virtual console ([booting a rescue
image, below][]).

[booting a rescue image, below]: #booting-a-rescue-image

Once an image is loaded, you should do a "quick network configuration"
in the grml menu (<kbd>n</kbd> key, or type `grml-network` in a
shell). This will fire up a dialog interface to enter the server's IP
address, netmask, gateway, and DNS. The first three should be
allocated from DNS (in the `82.229.38.in-addr.arpa.` file of the
`dns/domains.git` repository). The latter should be set to some public
nameserver for now (e.g. Google's 8.8.8.8).

Alternatively, you can use this one-liner to set IP address, DNS
servers and start SSH with your SSH key in root's list:

    echo nameserver 8.8.8.8 >> /etc/resolv.conf &&
    ip link set dev eth0 up &&
    ip addr add dev eth0 $address/$prefix &&
    ip route add default via $gateway &&
    mkdir -p /root/.ssh/ &&
    echo "$PUBLIC_KEY" >> /root/.ssh/authorized_keys &&
    service ssh restart

If you have booted with a serial console (which you should have), you
should also be able to extract the SSH public keys at this point,
with:

    sed "s/^/$address /" < /etc/ssh/ssh_host_*.pub

This can be copy-pasted into your `~/.ssh/known_hosts` file, or, to be
compatible with the installer script below, you should instead use:

    for key in /etc/ssh/ssh_host_*_key; do
        ssh-keygen -E md5 -l -f $key
    done

TODO: make the fabric installer accept non-md5 keys.

Phew! Now you have a shell you can use to bootstrap your installer.

## Automated install procedure

To install a new machine in the Cymru cluster, you first need to:

 1. configure the BIOS to display in the serial console (see [Serial console access](#serial-console-access))
 2. get [SSH access to the RACDM](#ssh-racdm-access)
 3. change the [admin iDRAC password](#idrac-password-reset)
 4. [bootstrap the installer](#bootstrapping-installer) through the virtual console and
    (optionally, because it's easier to copy-paste and debug) through
    the serial console

From there on, the machine can be bootstrapped with a basic Debian
installer with the [howto/Fabric](howto/Fabric) code in the `tsa-misc` git
repository. Here's an example of a commandline:

    ./install -H root@38.229.82.111 \
              --fingerprint da:aa:23:4b:8a:ef:5a:b3:2c:9b:6b:63:cb:36:e9:c1 \
              --verbose \
              hetzner-robot \
              --fqdn=chi-node-08.torproject.org \
              --boot-disk=/dev/sda \
              --fai-disk-config=installer/disk-config/gnt-chi-noraid \
              --package-list=installer/packages \
              --post-scripts-dir=installer/post-scripts/

Taking that apart:

 * `-H root@88.99.194.57`: the IP address picked from the zonefile
 * `--fingerprint`: the ed25519 MD5 fingerprint from the previous setup
 * `--verbose`: important for now because otherwise the job is silent
   except for errors, which could be confusing
 * `hetzner-robot`: the install job type (only robot supported for now)
 * `--fqdn=HOSTNAME.torproject.org`: the Fully Qualified Domain Name
   to set on the machine, it is used in a few places, but the
   `hostname` is correctly set to the `HOSTNAME` part only
 * `--boot-disk=/dev/sda`: which disk to install grub on
 * `--fai-disk-config=installer/disk-config/gnt-chi-noraid`: the disk
   configuration, in [fai-setup-storage(8)](https://manpages.debian.org/setup-storage.8) format
 * `--package-list=installer/packages`: the base packages to install
 * `--post-scripts-dir=installer/post-scripts/`: post-install scripts,
   magic glue that does everything
 
The last two are passed to `grml-debootstrap` and should rarely be
changed (although they could be converted in to Fabric tasks
themselves).

Note that the script will show you lines like:

    STEP 1: SSH into server with fingerprint ...

Those correspond to the manual install procedure, below. If the
procedure stops before the last step (currently STEP 12), there was a
problem in the procedure, but the remaining steps can still be
performed by hand.

If a problem occurs in the install, you can login to the rescue shell
with:

    ssh -o FingerprintHash=md5 -o UserKnownHostsFile=~/.ssh/authorized_keys.hetzner-rescue root@88.99.194.57

... and check the fingerprint against the previous one.

See [howto/new-machine](howto/new-machine) for post-install configuration steps, then follow
[howto/new-machine-mandos](howto/new-machine-mandos) for setting up the mandos client on this host.

IMPORTANT: Do not forget the extra configuration steps, below.

Note that it might be possible to run this installer over an existing,
on-disk install. But in my last attempts, it failed during
`setup-storage` while attempting to wipe the filesystems. Maybe a
`pivot_root` and unmounting everything would fix this, but at that
point it becomes a bit too complicated.

### remount procedure

If you need to do something post-install, this should bring you a
working shell in the `chroot`:

    cryptsetup luksOpen /dev/sda3 crypt_dev_sda3 &&
    vgchange -a y ; \
    mount /dev/mapper/vg_ganeti-root /mnt &&
    for fs in /run /sys /dev /proc; do mount -o bind $fs /mnt$fs; done &&
    mount /dev/sda2 /mnt/boot &&
    chroot /mnt /bin/bash

This will rebuild grub:

    chroot /mnt update-grub &&
    chroot /mnt grub-install /dev/sda

And this will cleanup the rest:

    umount /mnt/boot &&
    for fs in /dev /sys /run /proc; do umount /mnt$fs; done &&
    umount /mnt &&
    vgchange -a n &&
    cryptsetup luksClose crypt_dev_sda3

### Extra firmware

TODO: make sure this is automated somehow?

If you're getting this error on reboot:

    failed to load bnx2-mips-09-6.2.1b.fw firmware

Make sure `firmware-bnx2` is installed.

### IP address

TODO: in the last setup, the IP address had to be set in
`/etc/network/interfaces` by hand. The automated install assumes DHCP
works, which is not the case here.

TODO: IPv6 configuration also needs to be done by hand. hints in new-machine.

### serial console

Add this to the grub config to get the serial console working, in
(say) `/etc/default/grub.d/serial.cfg`:

```
# enable kernel's serial console on port 1 (or 0, if you count from there)
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX console=tty0 console=ttyS0,115200n8"
# same with grub itself
GRUB_TERMINAL="serial console"
GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"
```

Then enable the serial console login as well, for good measure:

    systemctl enable serial-getty@ttyS0.service
    systemctl start serial-getty@ttyS0.service

### initramfs boot config

TODO: figure out the best way to setup the initramfs. So far we've
dumped the IP address in `/etc/default/grub.d/local-ipaddress.cfg`
like so:

```
# for dropbear-initramfs because we don't have dhcp
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX ip=38.229.82.111::38.229.82.1:255.255.255.0::eth0:off"
```

... but it seems it's also possible to specify the IP by configuring
the initramfs itself, in `/etc/initramfs-tools/conf.d/ip`, for example
with:

    echo 'IP="${ip_address}::${gateway_ip}:${netmask}:${optional_fqdn}:${interface_name}:none"'

Then rebuild grub:

    update-grub

### iSCSI access

Make sure the node has access to the iSCSI cluster. For this, you need
to add the node on the SANs, using `SMcli`, using this magic script:

    create host userLabel="chi-node-0X" hostType=1 hostGroup="gnt-chi";
    create iscsiInitiator chapSecret="[REDACTED]" iscsiName="iqn.1993-08.org.debian:01:chi-node-04" userLabel="chi-node-0X-iscsi" host="chi-node-0X";

Make sure you set a strong password in `[REDACTED]`! That password
should already be set by Puppet (from Trocla) in
`/etc/iscsi/iscsid.conf`, on the client. See:

    grep node.session.auth.password /etc/iscsi/iscsid.conf

You might also need to actually login to the SAN. First make sure you
can see the SAN controllers on the network, with, for example, `chi-san-01`:

    iscsiadm -m discovery -t st -p 172.30.130.22

Then you need to login on all of those targets:

    iscsiadm -m node -T iqn.1984-05.com.dell:powervault.md3200i.6782bcb00063c6a5000000004ed6d655 --login

TODO: shouldn't this be done by Puppet?

Then you should see the devices in `lsblk` and `multipath -ll`, for
example, here's one disk on multiple controllers:

```
root@chi-node-08:~# multipath -ll
tb-build-03-srv (36782bcb00063c6a500000f88605b0aac) dm-6 DELL,MD32xxi
size=600G features='3 queue_if_no_path pg_init_retries 50' hwhandler='1 rdac' wp=rw
|-+- policy='service-time 0' prio=14 status=active
| |- 9:0:0:7  sds  65:32  active ready running
| |- 6:0:0:7  sdaa 65:160 active ready running
| `- 4:0:0:7  sdz  65:144 active ready running
`-+- policy='service-time 0' prio=9 status=enabled
  |- 3:0:0:7  sdg  8:96   active ready running
  |- 10:0:0:7 sdw  65:96  active ready running
  `- 11:0:0:7 sdx  65:112 active ready running
```

See the [storage servers](#storage-servers) section for more information.

## SSH RACDM access

Note: this might already be enabled. Try to connect to the host over
SSH before trying this.

Note that this requires console access, see the [idrac consoles
section below](#idrac-consoles) for more information.

It is important to enable the SSH server in the iDRAC so we have a
more reasonable serial console interface than the outdated Java-based
virtual console. (The SSH server is probably also outdated, but at
least copy-paste works without running an old Ubuntu virtual machine.)
To enable the SSH server, head for the management web interface and
then:

 1. in `iDRAC settings`, choose `Network`
 2. pick the `Services` tab in the top menu
 3. make sure the `Enabled` checkmark is ticked in the `SSH` section

Then you can access the RACDM interface over SSH.

## iDRAC password reset

WARNING: note that the password length is arbitrarily limited, and the
limit is not constant across different iDRAC interfaces. Some have 20
characters, some less (16 seems to work).

### Through the RACDM SSH interface

 1. locate the root user:

        racadm getconfig -u root

 2. modify its password, changing `$INDEX` with the index value found
    above, in the `cfgUserAdminIndex=$INDEX` field

        racadm config -g cfgUserAdmin -o cfgUserAdminPassword -i $INDEX newpassword

An example session:

    /admin1-> racadm getconfig -u root
    # cfgUserAdminIndex=2
    cfgUserAdminUserName=root
    # cfgUserAdminPassword=******** (Write-Only)
    cfgUserAdminEnable=1
    cfgUserAdminPrivilege=0x000001ff
    cfgUserAdminIpmiLanPrivilege=4
    cfgUserAdminIpmiSerialPrivilege=4
    cfgUserAdminSolEnable=1


    RAC1168: The RACADM "getconfig" command will be deprecated in a
    future version of iDRAC firmware. Run the RACADM 
    "racadm get" command to retrieve the iDRAC configuration parameters.
    For more information on the get command, run the RACADM command
    "racadm help get".

    /admin1-> racadm config -g cfgUserAdmin -o cfgUserAdminPassword -i 2 [REDACTED]
    Object value modified successfully


    RAC1169: The RACADM "config" command will be deprecated in a
    future version of iDRAC firmware. Run the RACADM 
    "racadm set" command to configure the iDRAC configuration parameters.
    For more information on the set command, run the RACADM command
    "racadm help set".

### Through the web interface

Before doing anything, the password should be reset in the
iDRAC. Head for the management interface, then:

 1. in `iDRAC settings`, choose `User Authentication`
 2. click the number next to the `root` user (normally `2`)
 3. click `Next`
 4. tick the `Change password` box and set a strong password, saved in
    the password manager
 5. click `Apply`

Note that this requires console access, see the [idrac consoles
section below](#idrac-consoles) for more information.

## Other BIOS configuration

 * disable `F1/F2 Prompt on Error` in `System BIOS Settings >
   Miscellaneous Settings`

Serial port and F2 config:

    racadm set BIOS.SerialCommSettings.SerialComm OnConRedirCom1
    racadm set BIOS.MiscSettings.ErrPrompt Disabled
    racadm jobqueue create BIOS.Setup.1-1

This will fail on older RACADM versions, use this instead:

    racadm config -g cfgSerial -o cfgSerialConsoleEnable 1
    racadm config -g cfgSerial -o cfgSerialBaudRate 115200

Doesn't seem to be possible to disable the prompt there.

See also the [serial console access documentation](#serial-console-access).

## idrac consoles

"Consoles", in this context, are interfaces that allows you to connect
to a server as if you you were there. They are sometimes called "out
of band management", "idrac" (Dell), IPMI (SuperMicro and others),
"KVM" (Keyboard, Video, Monitor) switches, or "serial console" (made
of serial ports).

Dell servers have a management interface called "IDRAC" or [DRAC](https://en.wikipedia.org/wiki/Dell_DRAC)
("Dell Remote Access Controller"). Servers at Cymru use iDRAC 7 which
has [upstream documentation](https://www.dell.com/support/manuals/ca/en/cabsdt1/integrated-dell-remote-access-cntrllr-7-v1.50.50/idrac7ug1.50.50-v1/overview?guid=guid-1442cb67-030e-474c-8cfd-2e12dd4cb7db&lang=en-us) ([PDF](https://topics-cdn.dell.com/pdf/integrated-dell-remote-access-cntrllr-7-v1.50.50_users-guide_en-us.pdf), [web archive](https://web.archive.org/web/20201014164547/https://topics-cdn.dell.com/pdf/integrated-dell-remote-access-cntrllr-7-v1.50.50_users-guide_en-us.pdf)).

There is a [Python client for DRAC](https://opendev.org/openstack/python-dracclient) which allows for changing BIOS
settings, but not much more.

### Management network access

Before doing anything, we need access to the management network, which
is isolated from the regular internet (see the [network topology](#network-topology)
for more information). 

#### IPsec

This can be done by configuring a "client" (i.e. a roaming [IPsec](howto/ipsec)
node) inside the cluster. Anarcat did so with such a config in the
[Puppet](howto/puppet) `profile::ganeti::chi` class with a [configuration
detailed in the IPsec docs](howto/ipsec#special-case-roaming-clients).

The TL;DR: once configured, this is, client side:

    ip a add 172.30.141.242/32 dev br0
    ipsec restart

On the server side (chi-node-01):

    sysctl net.ipv4.ip_forward=1

Those are the two settings that are not permanent and might not have
survived a reboot or a network disconnect.

Once that configuration is enabled, you should be able to ping inside
`172.30.140.0/24` from the client, for example:

    ping 172.30.140.110

Note that this configuration only works between `chi-node-13` and
`chi-node-01`. The IP `172.30.140.101` (currently `eth2` on
`chi-node-01`) is special and configured as a router *only* for the
iDRAC of `chi-node-13`. The router on the other nodes is
`172.30.140.1` which is incorrect, as it's the iDRAC of
`chi-node-01`. All this needs to be cleaned up and put in Puppet more
cleanly, see [issue 40128](https://gitlab.torproject.org/tpo/tpa/team/-/issues/40128).

An alternative to this is to use `sshuttle` to setup routing, which
avoids the need to setup a router (`net.ipv4.ip_forward=1` - although
that might be tightened up a bit to restrict to some interfaces?).

#### SOCKS5

Another alternative that was investigated in the setup (in [issue
40097](https://gitlab.torproject.org/tpo/tpa/team/-/issues/40097)) is to "simply" use `ssh -D` to setup a SOCKS proxy, which
works for most of the web interface, but obviously might not work with
the Java consoles. This simply works:

    ssh -D 9099 chi-node-03.torproject.org

Then setup `localhost:9099` as a SOCKS5 proxy in Firefox, that makes
the web interface directly accessible. For newer iDRAC consoles, there
is no Java stuff, so that works as well, which removes the need for
IPsec altogether.

Obviously, it's possible to SSH directly into the RACADM management
interfaces from the `chi-node-X` machines as well,.

### Virtual console

Typically, users will connect to the "virtual console" over a web
server. The "old" iDRAC 7 version we have deployed uses
a Java applet or ActiveX. In practice, the former Java applets just
totally fail in my experiments (even after [bypassing security](https://velenux.wordpress.com/2017/06/07/workaround-for-javaws-jnpl-error-cannot-grant-permissions-to-unsigned-jars/)
[twice](https://unix.stackexchange.com/questions/143805/running-unsigned-javaws-code)) so it's somewhat of a dead end. Apparently, this actually
works on Internet Explorer 11, presumably on Windows.

Note: newer iDRAC versions (e.g. on `chi-node-14`) work natively in
the web browser, so you do not need the following procedure at all.

An alternative is to boot an older Ubuntu release (e.g. [12.04](https://releases.ubuntu.com/12.04/),
[archive](https://old-releases.ubuntu.com/releases/precise/)) and run a web browser inside of that session. On Linux
distributions, the [GNOME Boxes](https://wiki.gnome.org/Apps/Boxes) application provides an easy,
no-brainer way to run such images. Alternatives include VirtualBox,
[virt-manager](https://virt-manager.org/) and others, of course. ([Vagrant](https://vagrantup.com/) might be an
option, but only has a 12.04 image ([hashicorp/precise64](https://app.vagrantup.com/hashicorp/boxes/precise64)) for
VirtualBox, which isn't in Debian ([anymore](https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=794466)).

 1. When booted in the VM, do this:

        sudo apt-get update
        sudo apt-get install icedtea-plugin

 2. start Firefox and connect to the management interface.
 
 3. You will be prompted for a username and password, then you will
    see the "Integrated Dell Remote Access Controller 7" page.

 4. Pick the `Console` tab, and hit the `Launch virtual console`
    button
 
 5. If all goes well, this should launch the "Java Web Start" command
    which will launch the Java applet. 

 6. This will prompt you for a zillion security warnings, accept them all

 7. If all the stars align correctly, you should get a window with a
    copy of the graphical display of the computer. 

Note that in my experience, the window starts off being minuscule. Hit
the "maximize" button (a square icon) to make it bigger.

#### Fixing arrow keys in the virtual console

Now, it's possible that an annoying bug will manifest itself at this
stage: because the Java applet was conceived to work with an old X11
version, the keycodes for the arrow keys may not work. Without these
keys, choosing an alternative boot option cannot be done.

To fix this we can use a custom library designed to fix this exact
problem with iDRAC web console:

https://github.com/anchor/idrac-kvm-keyboard-fix

The steps are:

 1. First install some dependencies:

        sudo apt-get install build-essential git libx11-dev

 2. Clone the repository:

        cd ~
        git clone https://github.com/anchor/idrac-kvm-keyboard-fix.git
        cd idrac-kvm-keyboard-fix

 3. Review the contents of the repository.

 4. Compile and install:

        make
        PATH="${PATH}:${HOME}/bin" make install

 5. In Firefox, open `about:preferences#applications`

 6. Next to "JNLP File" click the dropdown menu and select
    "Use other..."

 7. Select the executable at `~/bin/javaws-idrac`

 8. Close and launch the Virtual Console again

### Virtual machine basics

TODO: move this section (and the libvirt stuff above) to another page,
maybe [howto/kvm](howto/kvm)?

TODO: automate this setup.

Using the `virt-manager` is a fairly straightforward way to get a
Ubuntu Precise box up and running.

It might also be good to keep an *installed* Ubuntu release inside a
virtual machine, because the "boot from live image" approach works
only insofar as the machine doesn't crash. 

Somehow the Precise installer is broken and tries to setup a 2GB
partition for /, which fails during the install. You may have to redo
the partitioning by hand to fix that.

You will also need to change the `sources.list` to point all hosts at
`old-releases.ubuntu.com` instead of (say) `ca.archive.ubuntu.com` or
`security.ubuntu.com` to be able to get the "latest" packages
(including `spice-vdagent`, below). This may get you there, untested:

    sed -i 's/\([a-z]*\.archive\|security\)\.ubuntu\.com/old-releases.ubuntu.com/' /etc/apt/sources.list

Note that you should install the `spice-vdagent` (or is it
`xserver-xorg-video-qxl`?)  package to get proper resolution. In
practice, I couldn't make this work and instead hardcoded the
resolution in `/etc/default/grub` with:

    GRUB_GFXMODE=1280x720
    GRUB_GFXPAYLOAD_LINUX=keep

Thanks to [Louis-Philippe Veronneau for the tip](https://veronneau.org/how-to-capture-a-remote-irc-session-live.html).

If using `virt-manager`, make sure the `gir1.2-spiceclientgtk-3.0`
(package name may have changed) is installed otherwise you will get
the error "SpiceClientGtk missing".

Finally, note that libvirt and virt-manager do not seem to properly
configure NAT to be compatible with ipsec. The symptom of that problem
is that the other end of the IPsec tunnel can be pinged from the host,
but not the guest. A tcpdump will show that packets do not come out of
the external host interface with the right IP address, for example
here they come out of `192.168.0.177` instead of `172.30.141.244`:

    16:13:28.370324 IP 192.168.0.117 > 172.30.140.100: ICMP echo request, id 1779, seq 19, length 64

It's unclear why this is happening: it seems that the wrong IP is
being chosen by the MASQUERADE rule. Normally, it [should](https://serverfault.com/a/971270) pick the ip
that `ip route get` shows and that *does* show the right route:

    # ip route get 172.30.140.100
    172.30.140.100 via 192.168.0.1 dev eth1 table 220 src 172.30.141.244 uid 0 
        cache 

But somehow it doesn't. A workaround is to add a SNAT rule like this:

    iptables -t nat -I LIBVIRT_PRT 2 -s 192.168.122.0/24 '!' -d '192.168.122.0/24' -j SNAT --to-source 172.30.141.244

Note that the rules are stateful, so this won't take effect for an
existing route (e.g. for the IP you were pinging). Change to a
different target to confirm it works.

It might have been able to hack at `ip xfrm policy` instead, to be
researched further. Note that those problems somehow do not occur in
GNOME Boxes.

### Booting a rescue image

Using the virtual console, it's possible to boot the machine using an
ISO or floppy image. This is useful for example when attempting to
boot the Memtest86 program, when the usual Memtest86+ crashes or is
unable to complete tests.

> Note: It is also possible to load an ISO or floppy image (say for
> rescue) through the DRAC interface directly, in `Overview -> Server ->
> Attached media`. Unfortunately, only NFS and CIFS shares are
> supported, which is... not great. But we could, in theory, leverage
> this to rescue machines from each other on the network, but that would
> require setting up redundant NFS servers on the management interface,
> which is hardly practical.

It is possible to load an ISO through the virtual console, however.

This assumes you already have an ISO image to boot from locally (that
means inside the VM if that is how you got the virtual console
above). If not, try this:

    wget https://download.grml.org/grml64-full_2021.07.iso

PRO TIP: you can mount an ISO image *through* the virtual image by
presenting it as a CD/DVD driver. Then the Java virtual console will
notice it and that will save you from copying this file into the
virtual machine.

First, get a virtual console going (above). Then, you need to navigate
the menus:

 1. Choose the `Launch Virtual Media` option from the `Virtual Media`
    menu in the top left

 2. Click the `Add image` button

 3. Select the ISO or IMG image you have downloaded above
 
 4. Tick the checkbox of the image in the `Mapped` column

 5. **Keep that window open!** Bring the console back into focus

 6. If available, choose the `Virtual CD/DVD/ISO` option in the `Next Boot` menu

 7. Choose the `Reset system (warm boot)` option in the `Power` menu

If you haven't been able to change the `Next Boot` above, press
<kbd>F11</kbd> during boot to bring up the boot menu. Then choose
`Virtual CD` if you mapped an ISO, or `Virtual Floppy` for a IMG.

If those menus are not familiar, you might have a different iDRAC
version. Try those:

 1. Choose the `Map CD/DVD` from the `Virtual media` menu

 2. Choose the `Virtual CD/DVD/ISO` option in the `Next Boot` menu

 3. Choose the `Reset system (warm boot)` option in the `Power` menu

The BIOS should find the ISO image and **download it from your
computer** (or, rather, you'll upload it to the server) which will be
slow as hell, yes.

If you are booting a grml image, you should probably add the following
options to the Linux commandline (to save some typing, select the
`Boot options for grml64-full` -> `grml64-full: Serial console`:

    console=tty1 console=ttyS0,115200n8 ssh grml2ram

This will:

 1. activate the serial console
 2. start an SSH server with a random password
 3. load the grml squashfs image to RAM

Some of those arguments (like `ssh grml2ram`) are in the [grml
cheatcodes page](https://grml.org/cheatcodes/), others (like `console`) are [builtin to the Linux
kernel](https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html).

Once the system boots (and it will take a while, as parts of the disk
image will need to be transfered): you should be able to login through
the serial console instead. It should look something like this after a
few minutes:

    [  OK  ] Found device /dev/ttyS0.
    [  OK  ] Started Serial Getty on ttyS0.
    [  OK  ] Started D-Bus System Message Bus.


    grml64-full 2020.06 grml ttyS0

    grml login: root (automatic login)

    Linux grml 5.6.0-2-amd64 #1 SMP Debian 5.6.14-2 (2020-06-09) x86_64
    Grml - Linux for geeks
    
    root@grml ~ # 

From there, you have a shell and can do magic stuff. Note that the ISO
is still necessary to load some programs: only a minimal squashfs is
loaded. To load the entire image, use `toram` instead of `grml2ram`,
but note this will transfer the *entire* ISO image to the remote
server's core memory, which can take a long time depending on your
local bandwidth. On a 25/10mbps cable connexion, it took over 90
minutes to sync the image which, clearly, is not as practical as
loading the image on the fly.

### Boot timings

It takes about 4 minutes for the Cymru machines to reboot and get to
the LUKS password prompt.

 1. POST check ("Checking memory..."): 0s
 2. iDRAC setup: 45s
 3. BIOS loading: 55s
 4. PXE initialiation: 70s
 5. RAID controller: 75s
 6. CPLD: 1m25s
 7. Device scan ("Initializing firmware interfaces..."): 1m45
 8. Lifecycle controller: 2m45
 9. Scanning devices: 3m20
 10. Starting bootloader: 3m25
 11. Linux loading: 3m33
 12. LUKS prompt: 3m50

This is the time it takes to reach each step in the boot with a
"virtual media" (a grml ISO) loaded:

 1. POST check ("Checking memory..."): 0s
 2. iDRAC setup: 35s
 3. BIOS loading: 45s
 4. PXE initialiation: 60s
 5. RAID controller: 67s
 6. CPLD: 1m20s
 7. Device scan ("Initializing firmware interfaces..."): 1m37
 8. Lifecycle controller: 2m44
 9. Scanning devices: 3m15
 10. Starting bootloader: 3m30

Those timings were calculated in "wall clock" time, using a manually
operated stopwatch. The error is estimated to be around plus or minus
5 seconds.

### Serial console access

It's possible to connect to DRAC over SSH, telnet, with IPMItool (see
[all the interfaces](https://www.dell.com/support/manuals/ca/en/cabsdt1/integrated-dell-remote-access-cntrllr-7-v1.50.50/idrac7ug1.50.50-v1/interfaces-and-protocols-to-access-idrac7?guid=guid-d3ac26ac-c4d8-44be-b252-d14c2430a95c&lang=en-us)). Note that documentation refers to VNC access
as well, but it seems that feature is missing from our firmware.

Typing `connect` in the SSH interface connects to the serial
port. Another port can be picked with the `console` command, and the
`-h` option will also show backlog (limited to 8kb by default):

    console -h com2

That size can be changed with this command on the console:

    racadm config -g cfgSerial -o cfgSerialHistorySize 8192

The baud rate (default is 57600) can be changed with:

    racadm config -g cfgSerial -o cfgSerialBaudRate 115200

There are many more interesting "RAC" commands visible in the `racadm
help` output.

The BIOS can also display in the serial console by entering the
console (<kbd>F2</kbd> in the BIOS splash screen) and picking `System
BIOS settings -> Serial communications -> Serial communication -> On
with serial redirection via COM1`.

Pro tip. When the machine reboots, the following screen flashes really
quickly:

    Press the spacebar to pause...
    
    KEY MAPPING FOR CONSOLE REDIRECTION:
    
    Use the <ESC><1> key sequence for <F1>
    Use the <ESC><2> key sequence for <F2>
    Use the <ESC><0> key sequence for <F10>
    Use the <ESC><!> key sequence for <F11>
    Use the <ESC><@> key sequence for <F12>
    
    Use the <ESC><Ctrl><M> key sequence for <Ctrl><M>
    Use the <ESC><Ctrl><H> key sequence for <Ctrl><H>
    Use the <ESC><Ctrl><I> key sequence for <Ctrl><I>
    Use the <ESC><Ctrl><J> key sequence for <Ctrl><J>
    
    Use the <ESC><X><X> key sequence for <Alt><x>, where x is any letter
    key, and X is the upper case of that key
    
    Use the <ESC><R><ESC><r><ESC><R> key sequence for <Ctrl><Alt><Del>

So this can be useful to send the dreaded `F2` key through the serial
console, for example.

To end the console session, type `^\` (Control-backslash).

See also the [Other BIOS configuration](#other-bios-configuration)
section.

### Power management

The next boot device can be changed with the `cfgServerBootOnce`. To
reboot a server, use `racadm serveraction`, for example:

    racadm serveraction hardreset
    racadm serveraction powercycle

Current status is shown with:

    racadm serveraction powerstatus

This should be good enough to get us started. See also the [upstream
documentation](https://www.dell.com/support/manuals/en-ca/idrac7-8-lifecycle-controller-v2.50.50.50/idrac_2.50.50.50_racadm/serveraction?guid=guid-69ea52c5-153d-4369-b7c4-6694a3b9e0d4&lang=en-us).

### Reseting the iDRAC

It can happen that the management interface gets hung. In my case it
happened when I left a virtual machine disappear while connected to the
iDRAC console overnight. The problem was that the web console login
would just hang on "Verifying credentials".

The workaround is to reset the RAC with:

    racadm racreset soft

If that's not good enough, try `hard` instead of soft, see also the
(rather not much more helpful, I'm afraid) [upstream
documentation](https://www.dell.com/support/manuals/en-ca/idrac7-8-lifecycle-controller-v2.50.50.50/idrac_2.50.50.50_racadm/racreset?guid=guid-69ea52c5-153d-4369-b7c4-6694a3b9e0d4&lang=en-us).

### IP address change

To change the IP address of the iDRAC itself, you can use the `racadm
setniccfg` command:

    racadm setniccfg -s 172.30.140.13 255.255.255.0 172.30.140.101

It takes a while for the changes to take effect. In the [latest
change][] we actually lost access to the RACADM interface after 30
seconds, but it's unclear if that is because the VLAN was changed or
it is because the change took 30 seconds to take effect.

[latest change]: https://gitlab.torproject.org/tpo/tpa/team/-/issues/40097#note_2718312

More practically, it could be useful to use IPv6 instead of
renumbering that interface, since access is likely to be over
link-local addresses anyways. This will enable IPv6 on the iDRAC
interface and set a link-local address:

    racadm config -g cfgIPv6LanNetworking -o cfgIPv6Enable 1

The current network configuration (including the IPv6 link-local
address) can be found in:

    racadm getniccfg

See also [this helpful guide for more network settings](https://www.aftershox.com/2013/07/11/how-to-configure-a-dell-idrac-card-using-the-racadm-command-line-tool/), as the
official documentation is rather hard to parse.

### Other documentation

 * [Integrated Dell Remote Access Controller](https://www.dell.com/support/manuals/ca/en/cabsdt1/integrated-dell-remote-access-cntrllr-7-v1.50.50/idrac7ug1.50.50-v1/overview) ([PDF](https://dl.dell.com/topicspdf/integrated-dell-remote-access-cntrllr-7-v1.50.50_users-guide_en-us.pdf))
 * [iDRAC 8/7 v2.50.50.50 RACADM CLI Guide](https://www.dell.com/support/manuals/ca/en/cabsdt1/idrac7-8-lifecycle-controller-v2.50.50.50/idrac_2.50.50.50_racadm/introduction?guid=guid-6b6564ab-ee63-49ef-a7d6-47154c343841&lang=en-us) ([PDF](https://dl.dell.com/topicspdf/idrac7-8-lifecycle-controller-v2.50.50.50_reference-guide_en-us.pdf))
 * DSA also has [some tools to talk to DRAC externally](https://dsa.debian.org/howto/drac-reset/), but they
   are not public

## Hardware RAID

The hardware RAID documentation lives in [howto/raid](howto/raid), see
that document on how to recover from RAID failures and so on.

## Storage servers

To talk to the storage servers, you'll need first to install the
`SMcli` commandline tool, see the [install instructions](#san-management-tools-setup) for more
information on that.

In general, commands are in the form of:

    SMcli $ADDRESS -c -S "$SCRIPT;"

Where:

 * `$ADDRESS` is the management address (in `172.30.40.0/24`) of the
   storage server
 * `$SCRIPT` is a command, with a trailing semi-colon

All the commands are documented in the [upstream manual](https://topics-cdn.dell.com/pdf/powervault-md3200_CLI-Guide_en-us.pdf) (chapter
12 has all the commands listed alphabetically, but earlier chapters
have topical instructions as well). What follows is a subset of
those, with only the `$SCRIPT` part. So, for example, this script:

    show storageArray profile;

Would be executed with something like:

    SMcli 172.30.140.16 -c 'show storageArray profile;'

Be careful with quoting here: some scripts expect certain arguments to
be quoted, and those quotes should be properly escaped (or quoted) in
the shell.

Some scripts will require a password (for example to modify
disks). That should be provided with the `-p` argument. Make sure you
prefix the command with a "space" so it does not end up in the shell
history:

     SMcli 172.30.140.16 -p $PASSWORD -c 'create virtualDisk [...];'

Note the leading space. A safer approach is to use the `set session
password` command inside a script. For example, the equivalent command
to the above, with a script, would be this `script`:

    set session password $PASSWORD;
    create virtualDisk [...];

And then call this script:

    SMcli 172.30.140.16 -f script

### Dump all information about a server

This will dump a *lot* of information about a server. 

    show storageArray profile;

### Listing disks

Listing virtual disks, which are the ones visible from other nodes:

    show allVirtualDisks;

Listing physical disks:

    show allPhysicalDisks summary;

Details (like speed in RPMs) can also be seen with:

    show allPhysicalDisks;

### Host and group management

The existing machines in the `gnt-chi` cluster were all added at once,
alongside a group, with this script:

    show "Creating Host Group gnt-chi.";
    create hostGroup userLabel="gnt-chi";

    show "Creating Host chi-node-01 with Host Type Index 1 (Linux) on Host Group gnt-chi.";
    create host userLabel="chi-node-01" hostType=1 hostGroup="gnt-chi";
    show "Creating Host chi-node-02 with Host Type Index 1 (Linux) on Host Group gnt-chi.";
    create host userLabel="chi-node-02" hostType=1 hostGroup="gnt-chi";
    show "Creating Host chi-node-03 with Host Type Index 1 (Linux) on Host Group gnt-chi.";
    create host userLabel="chi-node-03" hostType=1 hostGroup="gnt-chi";
    show "Creating Host chi-node-04 with Host Type Index 1 (Linux) on Host Group gnt-chi.";
    create host userLabel="chi-node-04" hostType=1 hostGroup="gnt-chi";

    show "Creating iSCSI Initiator iqn.1993-08.org.debian:01:chi-node-01 with User Label chi-node-01-iscsi on host chi-node-01";
    create iscsiInitiator iscsiName="iqn.1993-08.org.debian:01:chi-node-01" userLabel="chi-node-01-iscsi" host="chi-node-01";
    show "Creating iSCSI Initiator iqn.1993-08.org.debian:01:chi-node-02 with User Label chi-node-02-iscsi on host chi-node-02";
    create iscsiInitiator iscsiName="iqn.1993-08.org.debian:01:chi-node-02" userLabel="chi-node-02-iscsi" host="chi-node-02";
    show "Creating iSCSI Initiator iqn.1993-08.org.debian:01:chi-node-03 with User Label chi-node-03-iscsi on host chi-node-03";
    create iscsiInitiator iscsiName="iqn.1993-08.org.debian:01:chi-node-03" userLabel="chi-node-03-iscsi" host="chi-node-03";
    show "Creating iSCSI Initiator iqn.1993-08.org.debian:01:chi-node-04 with User Label chi-node-04-iscsi on host chi-node-04";
    create iscsiInitiator iscsiName="iqn.1993-08.org.debian:01:chi-node-04" userLabel="chi-node-04-iscsi" host="chi-node-04";

For new machines, only this should be necessary:

    create host userLabel="chi-node-0X" hostType=1 hostGroup="gnt-chi";
    create iscsiInitiator iscsiName="iqn.1993-08.org.debian:01:chi-node-04" userLabel="chi-node-0X-iscsi" host="chi-node-0X";

The `iscsiName` setting is in `/etc/iscsi/initiatorname.iscsi`, which
is configured by Puppet to be derived from the hostname, so it can be
reliably guessed above.

To confirm the iSCSI initiator name, you can run this command on the
host:

    iscsiadm -m session -P 1 | grep 'Iface Initiatorname' | sort -u 

Note that the above doesn't take into account CHAP authentication,
covered below.

### CHAP authentication

While we trust the local network (iSCSI is, after all, in the clear),
as a safety precaution, we do have password-based ([CHAP](https://en.wikipedia.org/wiki/Challenge-Handshake_Authentication_Protocol))
authentication between the clients and the server. This is configured
on the `iscsiInitiator` object on the SAN, with a setting like:

    set iscsiInitiator ["chi-node-01-iscsi"] chapSecret="[REDACTED]";

The password comes from Trocla, in Puppet. It can be found in:

    grep node.session.auth.password /etc/iscsi/iscsid.conf

The client's "username" is the iSCSI initiator identifier, which maps
to the `iscsiName` setting on the SAN side. For `chi-node-01`, it
looks something like:

    iqn.1993-08.org.debian:01:chi-node-01

See above for details on the iSCSI initiator setup.

We do one way CHAP authentication (the clients authenticate to the
server). We do not do it both ways, because we have multiple SAN
servers and we haven't figured out how to make `iscsid` talk to
multiple SANs at once (there's only *one*
`node.session.auth.username_in`, and it's the iSCSI target identifier,
so it can't be the same across SANs).

### Creating a disk

This will create a disk:

    create virtualDisk physicalDiskCount=3 raidLevel=5 userLabel="anarcat-test" capacity=20GB;

Map that group to a Logical Unit Number (LUN):

    set virtualDisk ["anarcat-test"] logicalUnitNumber=3 hostGroup="gnt-chi";

Important: the LUN needs to be greater than 1, LUNs 0 and 1 are
special. It should be the current highest LUN plus one.

TODO: we should figure out if the LUN can be assigned automatically,
or how to find what the highest LUN currently is.

At this point, the device should show up on hosts in the `hostGroup`,
as multiple `/dev/sdX` (for example, `sdb`, `sdc`, ..., `sdg`, if
there are 6 "portals"). To work around that problem (and ensure high
availability), the device needs to be added with `multipath -a` on the
host:

    root@chi-node-01:~# multipath -a /dev/sdb && sleep 3 && multipath -r
    wwid '36782bcb00063c6a500000aa36036318d' added

To find the actual path to the device, given the LUN above, look into
`/dev/disk/by-path/ip-$ADDRESS-iscsi-$TARGET-lun-$LUN`, for example:

    root@chi-node-02:~# ls -al /dev/disk/by-path/*lun-3
    lrwxrwxrwx 1 root root 9 Mar  4 20:18 /dev/disk/by-path/ip-172.30.130.22:3260-iscsi-iqn.1984-05.com.dell:powervault.md3200i.6782bcb00063c6a5000000004ed6d655-lun-3 -> ../../sde
    lrwxrwxrwx 1 root root 9 Mar  4 20:18 /dev/disk/by-path/ip-172.30.130.23:3260-iscsi-iqn.1984-05.com.dell:powervault.md3200i.6782bcb00063c6a5000000004ed6d655-lun-3 -> ../../sdg
    lrwxrwxrwx 1 root root 9 Mar  4 20:18 /dev/disk/by-path/ip-172.30.130.24:3260-iscsi-iqn.1984-05.com.dell:powervault.md3200i.6782bcb00063c6a5000000004ed6d655-lun-3 -> ../../sdf
    lrwxrwxrwx 1 root root 9 Mar  4 20:18 /dev/disk/by-path/ip-172.30.130.26:3260-iscsi-iqn.1984-05.com.dell:powervault.md3200i.6782bcb00063c6a5000000004ed6d655-lun-3 -> ../../sdc
    lrwxrwxrwx 1 root root 9 Mar  4 20:18 /dev/disk/by-path/ip-172.30.130.27:3260-iscsi-iqn.1984-05.com.dell:powervault.md3200i.6782bcb00063c6a5000000004ed6d655-lun-3 -> ../../sdb
    lrwxrwxrwx 1 root root 9 Mar  4 20:18 /dev/disk/by-path/ip-172.30.130.28:3260-iscsi-iqn.1984-05.com.dell:powervault.md3200i.6782bcb00063c6a5000000004ed6d655-lun-3 -> ../../sdd

Then the device can be formatted, read and written to as a normal
device, in:

    /dev/mapper/36782bcb00063c6a500000aa36036318d

For example:

    mkfs.ext4 -j /dev/mapper/36782bcb00063c6a500000aa36036318d
    mount /dev/mapper/36782bcb00063c6a500000aa36036318d /mnt

To have a meaningful name in the device mapper, we need to add an
alias in the multipath daemon. First, you need to find the device
`wwid`:

    root@chi-node-01:~# /lib/udev/scsi_id -g -u -d /dev/sdl
    36782bcb00063c6a500000d67603f7abf

Then add this to the multipath configuration, with an alias, say in
`/etc/multipath/conf.d/web-chi-03-srv.conf`:

```
multipaths {
        multipath {
                wwid 36782bcb00063c6a500000d67603f7abf
                alias web-chi-03-srv
        }
}
```

Then reload the multipath configuration:

    multipath -r

Then add the device:

    multipath -a /dev/sdl

Then reload the multipathd configuration (yes, again):

    multipath -r

You should see the new device name in `multipath -ll`:

    root@chi-node-01:~# multipath -ll
    36782bcb00063c6a500000bfe603f465a dm-15 DELL,MD32xxi
    size=20G features='5 queue_if_no_path pg_init_retries 50 queue_mode mq' hwhandler='1 rdac' wp=rw
    web-chi-03-srv (36782bcb00063c6a500000d67603f7abf) dm-20 DELL,MD32xxi
    size=500G features='5 queue_if_no_path pg_init_retries 50 queue_mode mq' hwhandler='1 rdac' wp=rw
    |-+- policy='round-robin 0' prio=6 status=active
    | |- 11:0:0:4 sdi 8:128 active ready running
    | |- 12:0:0:4 sdj 8:144 active ready running
    | `- 9:0:0:4  sdh 8:112 active ready running
    `-+- policy='round-robin 0' prio=1 status=enabled
      |- 10:0:0:4 sdk 8:160 active ghost running
      |- 7:0:0:4  sdl 8:176 active ghost running
      `- 8:0:0:4  sdm 8:192 active ghost running
    root@chi-node-01:~#

And `lsblk`:

```
# lsblk
[...]
sdh                                                                   8:112  0   500G  0 disk  
└─web-chi-03-srv                                                    254:20   0   500G  0 mpath 
sdi                                                                   8:128  0   500G  0 disk  
└─web-chi-03-srv                                                    254:20   0   500G  0 mpath 
sdj                                                                   8:144  0   500G  0 disk  
└─web-chi-03-srv                                                    254:20   0   500G  0 mpath 
sdk                                                                   8:160  0   500G  0 disk  
└─web-chi-03-srv                                                    254:20   0   500G  0 mpath 
sdl                                                                   8:176  0   500G  0 disk  
└─web-chi-03-srv                                                    254:20   0   500G  0 mpath 
sdm                                                                   8:192  0   500G  0 disk  
└─web-chi-03-srv                                                    254:20   0   500G  0 mpath 
```

See [issue 40131](https://gitlab.torproject.org/tpo/tpa/team/-/issues/40131).

### Deleting a disk

Before you delete a disk, you should make sure nothing uses it
anymore. Where `$ALIAS` is the name of the device as seen from the
Linux nodes (either a multipath alias or WWID):

    gnt-cluster command "ls -l /dev/mapper/$ALIAS*"
    # and maybe:
    gnt-cluster command "kpartx -v -p -part -d /dev/mapper/$ALIAS"

Then you need to flush the multipath device somehow. The [DSA ganeti
install docs](https://dsa.debian.org/howto/install-ganeti/) have ideas, grep for "Remove LUNs". They basically do
`blockdev --flushbufs` on the multipath device, then `multipath -f`
the device, then `blockdev --flushbufs` on each underlying device. And
then they rescan the SCSI bus, using a sysfs file we don't have,
great.

TODO: see how (or if?) we need to run `blockdev --flushbufs` on the
multipath device, and how to guess the underlying block devices for
flushing.

To Unmap a LUN, which will stop making a disk available to a specific
host group:

    remove virtualDisks ["anarcat-test"] lunMapping;

This will actually not show up on the clients until they run:

    iscsiadm -m node --rescan

TODO: last time we tried this, the devices disappeared from `lsblk`,
but they were still in `/dev`. Only a `--logout` cleanly removed the
devices, which is obviously not practical.

To actually delete a disk:

    delete virtualDisk ["anarcat-test"];

... this will obviously complete the catastrophe, and lose all data
associated with the disk.

### Password change

This will set the password for the admin interface to `password`:

    set storageArray password="password";

### Health check

    show storageArray healthStatus;

### IP address dump

This will show the IP address configuration of all the controllers:

    show allControllers

A configured entry looks like this:

```
   RAID Controller Module in Enclosure 0, Slot 0
    

      Status:                      Online                                    
                                                                             
      Current configuration                                                  
         Firmware version:         07.80.41.60                               
            Appware version:       07.80.41.60                               
            Bootware version:      07.80.41.60                               
         NVSRAM version:           N26X0-780890-001                          
      Pending configuration                                                  
         Firmware version:         None                                      
            Appware version:       None                                      
            Bootware version:      None                                      
         NVSRAM version:           None                                      
         Transferred on:           None                                      
      Model name:                  2650                                      
      Board ID:                    2660                                      
      Submodel ID:                 143                                       
      Product ID:                  MD32xxi                                   
      Revision:                    0780                                      
      Replacement part number:     A00                                       
      Part number:                 0770D8                                    
      Serial number:               1A5009H                                   
      Vendor:                      DELL                                      
      Date of manufacture:         October 5, 2011                           
      Trunking supported:          No                                        
                                                                             
      Data Cache                                                             
         Total present:            1744 MB                                   
         Total used:               1744 MB                                   
      Processor cache:                                                       
         Total present:            304 MB                                    
      Cache Backup Device                                                    
         Status:                   Optimal                                   
         Type:                     SD flash physical disk                    
         Location:                 RAID Controller Module 0, Connector SD 1  
         Capacity:                 7,639 MB                                  
         Product ID:               Not Available                             
         Part number:              Not Available                             
         Serial number:            a0106234                                  
         Revision level:           10                                        
         Manufacturer:             Lexar                                     
         Date of manufacture:      August 1, 2011                            
      Host Interface Board                                                   
         Status:                   Optimal                                   
         Location:                 Slot 1                                    
         Type:                     iSCSI                                     
         Number of ports:          4                                         
         Board ID:                 0501                                      
         Replacement part number:  PN 0770D8A00                              
         Part number:              PN 0770D8                                 
         Serial number:            SN 1A5009H                                
         Vendor:                   VN 13740                                  
         Date of manufacture:      Not available                             
      Date/Time:                   Thu Feb 25 19:52:53 UTC 2021              

      Associated Virtual Disks (* = Preferred Owner): None


      RAID Controller Module DNS/Network name:   6MWKWR1   
         Remote login:                           Disabled  


      Ethernet port:              1                  
         Link status:             Up                 
         MAC address:             78:2b:cb:67:35:fd  
         Negotiation mode:        Auto-negotiate     
            Port speed:           1000 Mbps          
            Duplex mode:          Full duplex        
         Network configuration:   Static             
         IP address:              172.30.140.15      
         Subnet mask:             255.255.255.0      
         Gateway:                 172.30.140.1       
                                                     


      Physical Disk interface:  SAS     
         Channel:               1       
         Port:                  Out     
            Status:             Up      
         Maximum data rate:     6 Gbps  
         Current data rate:     6 Gbps  

      Physical Disk interface:  SAS     
         Channel:               2       
         Port:                  Out     
            Status:             Up      
         Maximum data rate:     6 Gbps  
         Current data rate:     6 Gbps  

      Host Interface(s): Unable to retrieve latest data; using last known state.


      Host interface:                                       iSCSI                           
         Host Interface Card(HIC):                          1                               
         Channel:                                           1                               
         Port:                                              0                               
         Link status:                                       Connected                       
         MAC address:                                       78:2b:cb:67:35:fe               
         Duplex mode:                                       Full duplex                     
         Current port speed:                                1000 Mbps                       
         Maximum port speed:                                1000 Mbps                       
         iSCSI RAID controller module                                                       
            Vendor:                                         ServerEngines Corporation       
            Part number:                                    ServerEngines SE-BE4210-S01     
            Serial number:                                  782bcb6735fe                    
            Firmware revision:                              2.300.310.15                    
         TCP listening port:                                3260                            
         Maximum transmission unit:                         9000 bytes/frame                
         ICMP PING responses:                               Enabled                         
         IPv4:                                              Enabled                         
            Network configuration:                          Static                          
            IP address:                                     172.30.130.22                   
               Configuration status:                        Configured                      
            Subnet mask:                                    255.255.255.0                   
            Gateway:                                        0.0.0.0                         
            Ethernet priority:                              Disabled                        
               Priority:                                    0                               
            Virtual LAN (VLAN):                             Disabled                        
               VLAN ID:                                     1                               
         IPv6:                                              Disabled                        
            Auto-configuration:                             Enabled                         
            Local IP address:                               fe80:0:0:0:7a2b:cbff:fe67:35fe  
               Configuration status:                        Unconfigured                    
            Routable IP address 1:                          0:0:0:0:0:0:0:0                 
               Configuration status:                        Unconfigured                    
            Routable IP address 2:                          0:0:0:0:0:0:0:0                 
               Configuration status:                        Unconfigured                    
            Router IP address:                              0:0:0:0:0:0:0:0                 
            Ethernet priority:                              Disabled                        
               Priority:                                    0                               
            Virtual LAN (VLAN):                             Disabled                        
               VLAN ID:                                     1                               
            Hop limit:                                      64                              
            Neighbor discovery                                                              
               Reachable time:                              30000 ms                        
               Retransmit time:                             1000 ms                         
               Stale timeout:                               30000 ms                        
               Duplicate address detection transmit count:  1                               

```

A disabled port would looks like:

```
      Host interface:                                       iSCSI                           
         Host Interface Card(HIC):                          1                               
         Channel:                                           4                               
         Port:                                              3                               
         Link status:                                       Disconnected                    
         MAC address:                                       78:2b:cb:67:36:01               
         Duplex mode:                                       Full duplex                     
         Current port speed:                                UNKNOWN                         
         Maximum port speed:                                1000 Mbps                       
         iSCSI RAID controller module                                                       
            Vendor:                                         ServerEngines Corporation       
            Part number:                                    ServerEngines SE-BE4210-S01     
            Serial number:                                  782bcb6735fe                    
            Firmware revision:                              2.300.310.15                    
         TCP listening port:                                3260                            
         Maximum transmission unit:                         9000 bytes/frame                
         ICMP PING responses:                               Enabled                         
         IPv4:                                              Enabled                         
            Network configuration:                          Static                          
            IP address:                                     172.30.130.25                   
               Configuration status:                        Unconfigured                    
            Subnet mask:                                    255.255.255.0                   
            Gateway:                                        0.0.0.0                         
            Ethernet priority:                              Disabled                        
               Priority:                                    0                               
            Virtual LAN (VLAN):                             Disabled                        
               VLAN ID:                                     1                               
         IPv6:                                              Disabled                        
            Auto-configuration:                             Enabled                         
            Local IP address:                               fe80:0:0:0:7a2b:cbff:fe67:3601  
               Configuration status:                        Unconfigured                    
            Routable IP address 1:                          0:0:0:0:0:0:0:0                 
               Configuration status:                        Unconfigured                    
            Routable IP address 2:                          0:0:0:0:0:0:0:0                 
               Configuration status:                        Unconfigured                    
            Router IP address:                              0:0:0:0:0:0:0:0                 
            Ethernet priority:                              Disabled                        
               Priority:                                    0                               
            Virtual LAN (VLAN):                             Disabled                        
               VLAN ID:                                     1                               
            Hop limit:                                      64                              
            Neighbor discovery                                                              
               Reachable time:                              30000 ms                        
               Retransmit time:                             1000 ms                         
               Stale timeout:                               30000 ms                        
               Duplicate address detection transmit count:  1                               

```

### Other random commands

Show how virtual drives map to specific LUN mappings:

    show storageArray lunmappings;

Save config to (local) disk:

    save storageArray configuration file="raid-01.conf" allconfig;

### iSCSI manual commands

Those are debugging commands that were used to test the system, and
should normally not be necessary. Those are basically managed
automatically by `iscsid`.

Discover storage units interfaces:

    iscsiadm -m discovery -t st -p 172.30.130.22

Pick one of those targets, then login:

    iscsiadm -m node -T iqn.1984-05.com.dell:powervault.md3200i.6782bcb00063c6a5000000004ed6d655 -p 172.30.130.22 --login

This will show details about the connexion, including your iSCSI
initiator name:

    iscsiadm -m session -P 1

This will also show recognized devices:

    iscsiadm -m session -P 3

This will disconnect from the iSCSI host:

    iscsiadm -m node -T iqn.1984-05.com.dell:powervault.md3200i.6782bcb00063c6a5000000004ed6d655 -p 172.30.130.22 --logout

And this will... rescan the host? Not actually sure *what* this does:

    iscsiadm -m node -T iqn.1984-05.com.dell:powervault.md3200i.6782bcb00063c6a5000000004ed6d655 -p 172.30.130.22 --rescan

Some of those commands were cargo-culted from [this guide](https://ittroubleshooter.in/examples-iscsiadm-command-linux/).

Note that the [deployment guide](https://downloads.dell.com/manuals/common/powervault-md3200i_deployment%20guide_en-us.pdf) has more information about network
topology and such configuration.

# Reference

## Points of presence

We actually have two points of presence at cymru: wherever the `moly`
machine is (and is deprecated, see [issue 29974](https://gitlab.torproject.org/legacy/trac/-/issues/29974)) and the `gnt-chi`
cluster. This documentation mostly concerns the latter.

## Hardware inventory

There are two main cluster of machines at the main PoP:

 * 13 old servers (mostly Dell R610 or R620 2xXeon with a maximum of
   386GB RAM per node and 2x500GB SAS disks)
 * 8 storage arrays (Dell MD1220 or MD3200 21TB)
 * 1 "newer" server(Dell PowerEdge R640 2 Xeon Gold 6230 CPU @ 2.10GHz
   (40 cores total), 1536 GB of RAM, 2x900GB SSD Intel(R) X550 4-port
   10G Ethernet NIC)

### Servers

The "servers" are named `chi-node-X`, where `X` is a digit from `01`
to `13`. They are generally used for the `gnt-chi` [Ganeti](howto/ganeti)
cluster, except for the last machine(s), assigned to bare-metal GitLab
services (see [issue 40095](https://gitlab.torproject.org/tpo/tpa/team/-/issues/40095) and [CI documentation](howto/ci)). Only a part
of the machines were actually deployed. Here's the exaustive list and
whether it is installed (checked):

 * [x] `chi-node-01`: Ganeti node ([#40065](https://gitlab.torproject.org/tpo/tpa/team/-/issues/40065)) (typically master)
 * [x] `chi-node-02`: Ganeti node ([#40066](https://gitlab.torproject.org/tpo/tpa/team/-/issues/40066))
 * [x] `chi-node-03`: Ganeti node ([#40067](https://gitlab.torproject.org/tpo/tpa/team/-/issues/40067))
 * [x] `chi-node-04`: Ganeti node ([#40068](https://gitlab.torproject.org/tpo/tpa/team/-/issues/40068))
 * [x] `chi-node-05`: empty Ganeti node ([#40365](https://gitlab.torproject.org/tpo/tpa/team/-/issues/40365)), kept for spare
       parts because of hardware issues ([#40377](https://gitlab.torproject.org/tpo/tpa/team/-/issues/40377))
 * [ ] `chi-node-06`: ([#40390](https://gitlab.torproject.org/tpo/tpa/team/-/issues/40390))
 * [ ] `chi-node-07`
 * [x] `chi-node-08`: Ganeti node ([#40410](https://gitlab.torproject.org/tpo/tpa/team/-/issues/40410))
 * [ ] `chi-node-09`
 * [ ] `chi-node-10`
 * [ ] `chi-node-11`: unreachable ([#40401](https://gitlab.torproject.org/tpo/tpa/team/-/issues/40401)]
 * [ ] `chi-node-12`
 * [x] `chi-node-13`: first test CI node
 * [x] `chi-node-14`: shadow simulator node (tpo/tpa/team#40279)

Memory capacity varies between nodes:

 * Nodes 1-4: 384GB (24x16GB)
 * 5-7: 96GB (12*8GB)
 * 8-10, 12-13: 192GB (24*8GB?)
 * 11: unknown (issue https://gitlab.torproject.org/tpo/tpa/team/-/issues/40401)

Also note that some of the uninstalled nodes above *have* some
operating system installed, by Cymru, but that system can be safely
wiped and replaced by the standard install procedure established in
this page.

### SAN cluster specifications

There are 4 Dell MD3220i iscsi hardware raid units. Each MD3220i has a
MD1220 expansion unit attached for a total of 48 900GB disks per unit
(head unit + expansion unit). This provides roughly 172 TB of raw
storage ((900GB x 192 disk)/1000) = 172 TB. These storage arrays are
quite flexible and provide the ability to create numerous independent
volume groups per unit. They also are capable of tagging spare disks
for auto disk replacement of failed hard drives.

Upstream has a [technical guide book](https://www.dell.com/downloads/global/products/pvaul/en/powervault-md3200i-md3220i-technical-guidebook-en.pdf) with more complete
specifications.

The machines do not run a regular operating system (like, say Linux),
or at least does not provide traditional commandline-based interfaces
like telnet, SSH or even a web interface. Operations are performed
through a proprietary tool called "SMcli", detailed below.

Here's the exaustive list of the hardware RAID units -- which we call
[SAN][] -- and whether it is correctly setup (checked):

 * [x] `chi-san-01`: ~28TiB total: 28 1TB 7200 RPM drives
 * [ ] `chi-san-02`: ~40TiB total: 40 1TB 7200 RPM drives
 * [ ] `chi-san-03`: ~36TiB total: 47 800GB 10000 RPM drives
 * [ ] `chi-san-04`: ~38TiB total, 48 800GB 10000 RPM drives 
 * Total: 144TiB, not counting mirrors (around 72TiB total in RAID-1,
   96TiB in RAID-5)

A node that is correctly setup has the correct host groups, hosts, and
iSCSI initiators setup, with CHAP passwords.

All SANs were checked for the following during the [original
setup](https://gitlab.torproject.org/tpo/tpa/team/-/issues/40131):

 * [x] batteries status ("optimal")
 * [x] correct labeling (`chi-san-0X`)
 * [ ] disk inventory (replace or disable all failing disks)
 * [ ] setup spares

Spare disks can easily be found at [harddrivesdirect.com](https://harddrivesdirect.com/dell_build_PowerVault_MD3220i.php), but are
fairly expensive for this platform (115$USD for 1TB 7.2k RPM, 145$USD
for 10kRPM). It seems like the highest density per drive they have
available is 2TB, which would give us about 80TiB per server, but at
the whopping cost of 12,440$USD ([$255 per unit in a 5-pack](https://harddrivesdirect.com/product_info.php?products_id=483015))!

It must be said that this site takes a heavy markup... The typical
drive used in the array (Seagate ST9900805SS, 1TB 7.2k RPM) sells for
[186$USD](https://www.harddrivesdirect.com/product_info.php?products_id=459510_ST9900805SS) right now, while it's [154$USD at NewEgg](https://www.newegg.ca/p/pl?d=ST9900805SS) and [90$USD
at Amazon](https://www.amazon.com/Seagate-Savvio-2-5-Inch-Internal-ST9900805SS/dp/B008HDKUKC/ref=sr_1_2?dchild=1&keywords=ST9900805SS&qid=1614802728&refinements=p_n_feature_four_browse-bin%3A676133011&rnid=676128011&s=pc&sr=1-2). Worse, a typical Seagate IronWolf 8TB SATA sells for
[516$USD](https://www.harddrivesdirect.com/product_info.php?products_id=493505_ST8000VN0022&PHPSESSID=4i2otsr7tndtnr97a53nd7sqt4) while [Newegg lists them at 290$USD](https://www.newegg.ca/p/pl?d=ST8000VN0022). That "same day
delivery" has a cost... And it's actually fairly hard to find those
old drives in other sites, so we probably pay a premium there as well.

### SAN management tools setup

The access the iSCSI servers, you need to setup the (proprietary)
SMCli utilities from Dell. First, you need to extract the software
from a ISO:

    apt install xorriso
    curl -o dell.iso https://downloads.dell.com/FOLDER04066625M/1/DELL_MDSS_Consolidated_RDVD_6_5_0_1.iso
    osirrox -indev dell.iso -extract /linux/mdsm/SMIA-LINUXX64.bin dell.bin
    ./dell.bin

Click through the installer, which will throw a bunch of junk
(including RPM files and a Java runtime!) inside `/opt`. To generate
and install a Debian package:

    alien --scripts /opt/dell/mdstoragemanager/*.rpm
    dpkg -i smruntime* smclient*

The scripts shipped by Dell assume that `/bin/sh` is a `bash` shell
(or, more precisely, that the `source` command exists, which is [not
POSIX](https://github.com/koalaman/shellcheck/wiki/SC3046)). So we need to patch that:

    sed -i '1s,#!/bin/sh,#!/bin/bash,' /opt/dell/mdstoragemanager/client/*

Then, if the tool works, at all, a command like this should yield some
output:

    SMcli 172.30.140.16 -c "show storageArray profile;"

... assuming there's a server on the other side, of course.

Note that those instructions derive partially from [the upstream
documentation](https://dl.dell.com/topicspdf/storage-sc2000_install-guide_en-us.pdf). The ISO can also be found from [the download
site](https://www.dell.com/support/home/en-ca/product-support/product/powervault-md3200i/drivers). See also [those instructions](https://storm.malditainternet.com/wp/en//wp/2014/01/como-instalar-el-dell-powervault-md-storage-manager-en-ubuntu).

### iSCSI initiator setup

The iSCSI setup on the Linux side of things is handled automatically
by Puppet, in the `profile::iscsi` class, which is included in the
`profile::ganeti::chi` class. That will setup packages, configuration,
and passwords for iSCSI clients.

There still needs to be some manual configuration for the SANs to be
found.

Discover the array:

    iscsiadm -m discovery -t sendtargets -p 172.30.130.22

From there on, the devices exported to this initiator should show up
in `lsblk`, `fdisk -l`, `/proc/partitions`, or `lsscsi`, for example:

```
root@chi-node-01:~# lsscsi  | grep /dev/
[0:2:0:0]    disk    DELL     PERC H710P       3.13  /dev/sda 
[5:0:0:0]    cd/dvd  HL-DT-ST DVD-ROM DU70N    D300  /dev/sr0 
[7:0:0:3]    disk    DELL     MD32xxi          0780  /dev/sde 
[8:0:0:3]    disk    DELL     MD32xxi          0780  /dev/sdg 
[9:0:0:3]    disk    DELL     MD32xxi          0780  /dev/sdb 
[10:0:0:3]   disk    DELL     MD32xxi          0780  /dev/sdd 
[11:0:0:3]   disk    DELL     MD32xxi          0780  /dev/sdf 
[12:0:0:3]   disk    DELL     MD32xxi          0780  /dev/sdc 
```

Next you need to actually add the disk to multipath, with:

    multipath -a /dev/sdb

For example:

    # multipath -a /dev/sdb
    wwid '36782bcb00063c6a500000aa36036318d' added

Then the device is available as a unique device in:

    /dev/mapper/36782bcb00063c6a500000aa36036318d

... even though there are multiple underlying devices.

## Benchmarks

Overall, the hardware in the gnt-chi cluster is dated, mainly because
it lacks fast SSD disks. It can still get respectable performance,
because the disks were top of the line when they were setup. In
general, you should expect:

 * local (small) disks:
   * read: IOPS=1148, BW=4595KiB/s (4706kB/s)
   * write: IOPS=2213, BW=8854KiB/s (9067kB/s)
 * iSCSI (network, large) disks:
   * read: IOPS=26.9k, BW=105MiB/s (110MB/s) (gigabit network
     saturation, probably cached by the SAN)
   * random write: IOPS=264, BW=1059KiB/s (1085kB/s)
   * sequential write: 11MB/s (dd)

In other words, local disks can't quite saturate network (far from it:
they don't even saturate a 100mbps link). Network disks seem to be
able to saturate gigabit at first glance, but that's probably a
limitation of the benchmark. Writes are much slower, somewhere around
8mbps.

Compare this with a more modern setup:

 * NVMe:
   * read: IOPS=138k, BW=541MiB/s (567MB/s)
   * write: IOPS=115k, BW=448MiB/s (470MB/s)
 * SATA:
   * read: IOPS=5550, BW=21.7MiB/s (22.7MB/s)
   * write: IOPS=199, BW=796KiB/s (815kB/s)

Notice how the large disk writes are actually *lower* than the iSCSI
store in this case, but this could be a fluke because of the existing
load on the gnt-fsn cluster.

### Onboard SAS disks, chi-node-01

    root@chi-node-01:~/bench# fio --name=stressant --group_reporting <(sed /^filename=/d /usr/share/doc/fio/examples/basic-verify.fio) --runtime=1m  --filename=test --size=100m
    stressant: (g=0): rw=read, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=psync, iodepth=1
    write-and-verify: (g=0): rw=randwrite, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=libaio, iodepth=16
    fio-3.12
    Starting 2 processes
    stressant: Laying out IO file (1 file / 100MiB)
    Jobs: 1 (f=1): [_(1),V(1)][94.3%][r=104MiB/s][r=26.6k IOPS][eta 00m:21s]                
    stressant: (groupid=0, jobs=1): err= 0: pid=13409: Wed Mar 24 17:40:23 2021
      read: IOPS=150k, BW=585MiB/s (613MB/s)(100MiB/171msec)
        clat (nsec): min=980, max=1033.1k, avg=6290.36, stdev=46177.07
         lat (nsec): min=1015, max=1033.1k, avg=6329.40, stdev=46177.22
        clat percentiles (nsec):
         |  1.00th=[  1032],  5.00th=[  1048], 10.00th=[  1064], 20.00th=[  1096],
         | 30.00th=[  1128], 40.00th=[  1144], 50.00th=[  1176], 60.00th=[  1192],
         | 70.00th=[  1224], 80.00th=[  1272], 90.00th=[  1432], 95.00th=[  1816],
         | 99.00th=[244736], 99.50th=[428032], 99.90th=[618496], 99.95th=[692224],
         | 99.99th=[774144]
      lat (nsec)   : 1000=0.03%
      lat (usec)   : 2=97.01%, 4=0.84%, 10=0.07%, 20=0.47%, 50=0.13%
      lat (usec)   : 100=0.12%, 250=0.35%, 500=0.68%, 750=0.29%, 1000=0.01%
      lat (msec)   : 2=0.01%
      cpu          : usr=8.82%, sys=27.65%, ctx=372, majf=0, minf=12
      IO depths    : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
         submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
         complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
         issued rwts: total=25600,0,0,0 short=0,0,0,0 dropped=0,0,0,0
         latency   : target=0, window=0, percentile=100.00%, depth=1
    write-and-verify: (groupid=0, jobs=1): err= 0: pid=13410: Wed Mar 24 17:40:23 2021
      read: IOPS=1148, BW=4595KiB/s (4706kB/s)(1024MiB/228181msec)
        slat (usec): min=5, max=547, avg=21.60, stdev= 8.70
        clat (usec): min=22, max=767720, avg=13899.92, stdev=26025.10
         lat (usec): min=42, max=767773, avg=13921.96, stdev=26027.93
        clat percentiles (usec):
         |  1.00th=[    42],  5.00th=[    51], 10.00th=[    56], 20.00th=[    65],
         | 30.00th=[   117], 40.00th=[   200], 50.00th=[  4146], 60.00th=[  8029],
         | 70.00th=[ 13566], 80.00th=[ 21890], 90.00th=[ 39060], 95.00th=[ 60031],
         | 99.00th=[123208], 99.50th=[156238], 99.90th=[244319], 99.95th=[287310],
         | 99.99th=[400557]
      write: IOPS=2213, BW=8854KiB/s (9067kB/s)(1024MiB/118428msec); 0 zone resets
        slat (usec): min=6, max=104014, avg=36.98, stdev=364.05
        clat (usec): min=62, max=887491, avg=7187.20, stdev=7152.34
         lat (usec): min=72, max=887519, avg=7224.67, stdev=7165.15
        clat percentiles (usec):
         |  1.00th=[  157],  5.00th=[  383], 10.00th=[  922], 20.00th=[ 1909],
         | 30.00th=[ 2606], 40.00th=[ 3261], 50.00th=[ 4146], 60.00th=[ 7111],
         | 70.00th=[10421], 80.00th=[13042], 90.00th=[15795], 95.00th=[18220],
         | 99.00th=[25822], 99.50th=[32900], 99.90th=[65274], 99.95th=[72877],
         | 99.99th=[94897]
       bw (  KiB/s): min= 4704, max=95944, per=99.93%, avg=8847.51, stdev=6512.44, samples=237
       iops        : min= 1176, max=23986, avg=2211.85, stdev=1628.11, samples=237
      lat (usec)   : 50=2.27%, 100=11.27%, 250=10.32%, 500=1.76%, 750=1.19%
      lat (usec)   : 1000=0.86%
      lat (msec)   : 2=5.57%, 4=15.85%, 10=17.35%, 20=21.25%, 50=8.72%
      lat (msec)   : 100=2.72%, 250=0.82%, 500=0.04%, 750=0.01%, 1000=0.01%
      cpu          : usr=1.67%, sys=4.52%, ctx=296808, majf=0, minf=7562
      IO depths    : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=100.0%, 32=0.0%, >=64=0.0%
         submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
         complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.1%, 32=0.0%, 64=0.0%, >=64=0.0%
         issued rwts: total=262144,262144,0,0 short=0,0,0,0 dropped=0,0,0,0
         latency   : target=0, window=0, percentile=100.00%, depth=16

    Run status group 0 (all jobs):
       READ: bw=5044KiB/s (5165kB/s), 4595KiB/s-585MiB/s (4706kB/s-613MB/s), io=1124MiB (1179MB), run=171-228181msec
      WRITE: bw=8854KiB/s (9067kB/s), 8854KiB/s-8854KiB/s (9067kB/s-9067kB/s), io=1024MiB (1074MB), run=118428-118428msec

    Disk stats (read/write):
        dm-1: ios=262548/275002, merge=0/0, ticks=3635324/2162480, in_queue=5799708, util=100.00%, aggrios=262642/276055, aggrmerge=0/0, aggrticks=3640764/2166784, aggrin_queue=5807820, aggrutil=100.00%
        dm-0: ios=262642/276055, merge=0/0, ticks=3640764/2166784, in_queue=5807820, util=100.00%, aggrios=262642/267970, aggrmerge=0/8085, aggrticks=3633173/1921094, aggrin_queue=5507676, aggrutil=99.16%
      sda: ios=262642/267970, merge=0/8085, ticks=3633173/1921094, in_queue=5507676, util=99.16%

### iSCSI load testing, chi-node-01

    root@chi-node-01:/mnt# fio --name=stressant --group_reporting <(sed /^filename=/d /usr/share/doc/fio/examples/basic-verify.fio; echo size=100m) --runtime=1m  --filename=test --size=100m
    stressant: (g=0): rw=read, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=psync, iodepth=1
    write-and-verify: (g=0): rw=randwrite, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=libaio, iodepth=16
    fio-3.12
    Starting 2 processes
    write-and-verify: Laying out IO file (1 file / 100MiB)
    Jobs: 1 (f=0): [_(1),f(1)][100.0%][r=88.9MiB/s][r=22.8k IOPS][eta 00m:00s]               
    stressant: (groupid=0, jobs=1): err= 0: pid=18332: Wed Mar 24 17:56:02 2021
      read: IOPS=26.9k, BW=105MiB/s (110MB/s)(100MiB/952msec)
        clat (nsec): min=1214, max=7423.1k, avg=35799.85, stdev=324182.56
         lat (nsec): min=1252, max=7423.2k, avg=35889.53, stdev=324181.89
        clat percentiles (nsec):
         |  1.00th=[   1400],  5.00th=[   2128], 10.00th=[   2288],
         | 20.00th=[   2512], 30.00th=[   2576], 40.00th=[   2608],
         | 50.00th=[   2608], 60.00th=[   2640], 70.00th=[   2672],
         | 80.00th=[   2704], 90.00th=[   2800], 95.00th=[   3440],
         | 99.00th=[ 782336], 99.50th=[3391488], 99.90th=[4227072],
         | 99.95th=[4358144], 99.99th=[4620288]
       bw (  KiB/s): min=105440, max=105440, per=55.81%, avg=105440.00, stdev= 0.00, samples=1
       iops        : min=26360, max=26360, avg=26360.00, stdev= 0.00, samples=1
      lat (usec)   : 2=3.30%, 4=92.34%, 10=2.05%, 20=0.65%, 50=0.08%
      lat (usec)   : 100=0.01%, 250=0.11%, 500=0.16%, 750=0.28%, 1000=0.11%
      lat (msec)   : 2=0.11%, 4=0.67%, 10=0.13%
      cpu          : usr=4.94%, sys=12.83%, ctx=382, majf=0, minf=12
      IO depths    : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
         submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
         complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
         issued rwts: total=25600,0,0,0 short=0,0,0,0 dropped=0,0,0,0
         latency   : target=0, window=0, percentile=100.00%, depth=1
    write-and-verify: (groupid=0, jobs=1): err= 0: pid=18333: Wed Mar 24 17:56:02 2021
      read: IOPS=23.6k, BW=92.2MiB/s (96.7MB/s)(100MiB/1084msec)
        slat (nsec): min=6524, max=66741, avg=15619.91, stdev=6159.27
        clat (usec): min=331, max=52833, avg=658.14, stdev=1305.45
         lat (usec): min=355, max=52852, avg=674.08, stdev=1305.57
        clat percentiles (usec):
         |  1.00th=[  420],  5.00th=[  469], 10.00th=[  502], 20.00th=[  537],
         | 30.00th=[  570], 40.00th=[  594], 50.00th=[  619], 60.00th=[  644],
         | 70.00th=[  676], 80.00th=[  709], 90.00th=[  758], 95.00th=[  799],
         | 99.00th=[  881], 99.50th=[  914], 99.90th=[ 1188], 99.95th=[52691],
         | 99.99th=[52691]
      write: IOPS=264, BW=1059KiB/s (1085kB/s)(100MiB/96682msec); 0 zone resets
        slat (usec): min=15, max=110293, avg=112.91, stdev=1199.05
        clat (msec): min=3, max=593, avg=60.30, stdev=52.88
         lat (msec): min=3, max=594, avg=60.41, stdev=52.90
        clat percentiles (msec):
         |  1.00th=[   12],  5.00th=[   15], 10.00th=[   17], 20.00th=[   23],
         | 30.00th=[   29], 40.00th=[   35], 50.00th=[   44], 60.00th=[   54],
         | 70.00th=[   68], 80.00th=[   89], 90.00th=[  126], 95.00th=[  165],
         | 99.00th=[  259], 99.50th=[  300], 99.90th=[  426], 99.95th=[  489],
         | 99.99th=[  592]
       bw (  KiB/s): min=  176, max= 1328, per=99.67%, avg=1055.51, stdev=127.13, samples=194
       iops        : min=   44, max=  332, avg=263.86, stdev=31.78, samples=194
      lat (usec)   : 500=4.96%, 750=39.50%, 1000=5.42%
      lat (msec)   : 2=0.08%, 4=0.01%, 10=0.27%, 20=7.64%, 50=20.38%
      lat (msec)   : 100=13.81%, 250=7.34%, 500=0.56%, 750=0.02%
      cpu          : usr=0.88%, sys=3.13%, ctx=34211, majf=0, minf=628
      IO depths    : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=99.9%, 32=0.0%, >=64=0.0%
         submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
         complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.1%, 32=0.0%, 64=0.0%, >=64=0.0%
         issued rwts: total=25600,25600,0,0 short=0,0,0,0 dropped=0,0,0,0
         latency   : target=0, window=0, percentile=100.00%, depth=16

    Run status group 0 (all jobs):
       READ: bw=185MiB/s (193MB/s), 92.2MiB/s-105MiB/s (96.7MB/s-110MB/s), io=200MiB (210MB), run=952-1084msec
      WRITE: bw=1059KiB/s (1085kB/s), 1059KiB/s-1059KiB/s (1085kB/s-1085kB/s), io=100MiB (105MB), run=96682-96682msec

    Disk stats (read/write):
        dm-28: ios=22019/25723, merge=0/1157, ticks=16070/1557068, in_queue=1572636, util=99.98%, aggrios=4341/4288, aggrmerge=0/0, aggrticks=3089/259432, aggrin_queue=262419, aggrutil=99.79%
      sdm: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%
      sdk: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%
      sdi: ios=8686/8573, merge=0/0, ticks=6409/526657, in_queue=532844, util=99.79%
      sdl: ios=8683/8576, merge=0/0, ticks=6091/513333, in_queue=519120, util=99.75%
      sdj: ios=8678/8580, merge=0/0, ticks=6036/516604, in_queue=522552, util=99.77%
      sdh: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%

### Raw DD test, iSCSI disks, chi-node-04

`dd` fares much better, possibly because we're doing sequential writing:

    root@chi-node-04:/var/log/ganeti/os# dd if=/dev/zero of=/dev/disk/by-id/dm-name-tb-builder-03-root status=progress
    10735108608 bytes (11 GB, 10 GiB) copied, 911 s, 11.8 MB/s
    dd: writing to '/dev/disk/by-id/dm-name-tb-builder-03-root': No space left on device
    20971521+0 records in
    20971520+0 records out
    10737418240 bytes (11 GB, 10 GiB) copied, 914.376 s, 11.7 MB/s

### Comparison, NVMe disks, fsn-node-07

    root@fsn-node-07:~# fio --name=stressant --group_reporting <(sed /^filename=/d /usr/share/doc/fio/examples/basic-verify.fio; echo size=100m) --runtime=1m  --filename=test --size=100m
    stressant: (g=0): rw=read, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=psync, iodepth=1
    write-and-verify: (g=0): rw=randwrite, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=libaio, iodepth=16
    fio-3.12
    Starting 2 processes
    write-and-verify: Laying out IO file (1 file / 100MiB)

    stressant: (groupid=0, jobs=1): err= 0: pid=31809: Wed Mar 24 17:49:48 2021
      read: IOPS=138k, BW=541MiB/s (567MB/s)(100MiB/185msec)
        clat (nsec): min=522, max=2651.8k, avg=6848.59, stdev=57695.32
         lat (nsec): min=539, max=2651.8k, avg=6871.47, stdev=57695.33
        clat percentiles (nsec):
         |  1.00th=[    540],  5.00th=[    556], 10.00th=[    572],
         | 20.00th=[    588], 30.00th=[    596], 40.00th=[    612],
         | 50.00th=[    628], 60.00th=[    644], 70.00th=[    692],
         | 80.00th=[    764], 90.00th=[    828], 95.00th=[    996],
         | 99.00th=[ 292864], 99.50th=[ 456704], 99.90th=[ 708608],
         | 99.95th=[ 864256], 99.99th=[1531904]
      lat (nsec)   : 750=77.95%, 1000=17.12%
      lat (usec)   : 2=2.91%, 4=0.09%, 10=0.21%, 20=0.12%, 50=0.09%
      lat (usec)   : 100=0.04%, 250=0.32%, 500=0.77%, 750=0.28%, 1000=0.06%
      lat (msec)   : 2=0.03%, 4=0.01%
      cpu          : usr=10.33%, sys=10.33%, ctx=459, majf=0, minf=11
      IO depths    : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
         submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
         complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
         issued rwts: total=25600,0,0,0 short=0,0,0,0 dropped=0,0,0,0
         latency   : target=0, window=0, percentile=100.00%, depth=1
    write-and-verify: (groupid=0, jobs=1): err= 0: pid=31810: Wed Mar 24 17:49:48 2021
      read: IOPS=145k, BW=565MiB/s (592MB/s)(100MiB/177msec)
        slat (usec): min=2, max=153, avg= 3.28, stdev= 1.95
        clat (usec): min=23, max=740, avg=106.23, stdev=44.45
         lat (usec): min=25, max=743, avg=109.56, stdev=44.52
        clat percentiles (usec):
         |  1.00th=[   56],  5.00th=[   70], 10.00th=[   73], 20.00th=[   77],
         | 30.00th=[   82], 40.00th=[   87], 50.00th=[   93], 60.00th=[  101],
         | 70.00th=[  115], 80.00th=[  130], 90.00th=[  155], 95.00th=[  182],
         | 99.00th=[  269], 99.50th=[  343], 99.90th=[  486], 99.95th=[  537],
         | 99.99th=[  717]
      write: IOPS=115k, BW=448MiB/s (470MB/s)(100MiB/223msec); 0 zone resets
        slat (usec): min=4, max=160, avg= 6.10, stdev= 2.02
        clat (usec): min=31, max=15535, avg=132.13, stdev=232.65
         lat (usec): min=37, max=15546, avg=138.27, stdev=232.65
        clat percentiles (usec):
         |  1.00th=[   76],  5.00th=[   90], 10.00th=[   97], 20.00th=[  102],
         | 30.00th=[  106], 40.00th=[  113], 50.00th=[  118], 60.00th=[  123],
         | 70.00th=[  128], 80.00th=[  137], 90.00th=[  161], 95.00th=[  184],
         | 99.00th=[  243], 99.50th=[  302], 99.90th=[ 4293], 99.95th=[ 6915],
         | 99.99th=[ 6980]
      lat (usec)   : 50=0.28%, 100=36.99%, 250=61.67%, 500=0.89%, 750=0.04%
      lat (usec)   : 1000=0.01%
      lat (msec)   : 2=0.02%, 4=0.03%, 10=0.06%, 20=0.01%
      cpu          : usr=22.11%, sys=57.79%, ctx=8799, majf=0, minf=623
      IO depths    : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=99.9%, 32=0.0%, >=64=0.0%
         submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
         complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.1%, 32=0.0%, 64=0.0%, >=64=0.0%
         issued rwts: total=25600,25600,0,0 short=0,0,0,0 dropped=0,0,0,0
         latency   : target=0, window=0, percentile=100.00%, depth=16

    Run status group 0 (all jobs):
       READ: bw=1081MiB/s (1134MB/s), 541MiB/s-565MiB/s (567MB/s-592MB/s), io=200MiB (210MB), run=177-185msec
      WRITE: bw=448MiB/s (470MB/s), 448MiB/s-448MiB/s (470MB/s-470MB/s), io=100MiB (105MB), run=223-223msec

    Disk stats (read/write):
        dm-1: ios=25869/25600, merge=0/0, ticks=2856/2388, in_queue=5248, util=80.32%, aggrios=26004/25712, aggrmerge=0/0, aggrticks=2852/2380, aggrin_queue=5228, aggrutil=69.81%
        dm-0: ios=26004/25712, merge=0/0, ticks=2852/2380, in_queue=5228, util=69.81%, aggrios=26005/25712, aggrmerge=0/0, aggrticks=0/0, aggrin_queue=0, aggrutil=0.00%
        md1: ios=26005/25712, merge=0/0, ticks=0/0, in_queue=0, util=0.00%, aggrios=13002/25628, aggrmerge=0/85, aggrticks=1328/1147, aggrin_queue=2752, aggrutil=89.35%
      nvme0n1: ios=12671/25628, merge=0/85, ticks=1176/496, in_queue=1896, util=89.35%
      nvme1n1: ios=13333/25628, merge=1/85, ticks=1481/1798, in_queue=3608, util=89.35%

### Comparison, SATA disks, fsn-node-02

    root@fsn-node-02:/mnt# fio --name=stressant --group_reporting <(sed /^filename=/d /usr/share/doc/fio/examples/basic-verify.fio; echo size=100m) --runtime=1m  --filename=test --size=100m
    stressant: (g=0): rw=read, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=psync, iodepth=1
    write-and-verify: (g=0): rw=randwrite, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=libaio, iodepth=16
    fio-3.12
    Starting 2 processes
    write-and-verify: Laying out IO file (1 file / 100MiB)
    Jobs: 1 (f=0): [_(1),f(1)][100.0%][r=348KiB/s][r=87 IOPS][eta 00m:00s]                   
    stressant: (groupid=0, jobs=1): err= 0: pid=9635: Wed Mar 24 17:50:32 2021
      read: IOPS=5550, BW=21.7MiB/s (22.7MB/s)(100MiB/4612msec)
        clat (nsec): min=500, max=273948k, avg=179390.97, stdev=4673600.03
         lat (nsec): min=515, max=273948k, avg=179471.70, stdev=4673600.38
        clat percentiles (nsec):
         |  1.00th=[      524],  5.00th=[      580], 10.00th=[      692],
         | 20.00th=[     1240], 30.00th=[     1496], 40.00th=[     2320],
         | 50.00th=[     2352], 60.00th=[     2896], 70.00th=[     2960],
         | 80.00th=[     3024], 90.00th=[     3472], 95.00th=[     3824],
         | 99.00th=[   806912], 99.50th=[   978944], 99.90th=[ 60030976],
         | 99.95th=[110624768], 99.99th=[244318208]
       bw (  KiB/s): min= 2048, max=82944, per=100.00%, avg=22296.89, stdev=26433.89, samples=9
       iops        : min=  512, max=20736, avg=5574.22, stdev=6608.47, samples=9
      lat (nsec)   : 750=11.57%, 1000=3.11%
      lat (usec)   : 2=23.35%, 4=58.17%, 10=1.90%, 20=0.16%, 50=0.15%
      lat (usec)   : 100=0.03%, 250=0.03%, 500=0.04%, 750=0.32%, 1000=0.69%
      lat (msec)   : 2=0.17%, 4=0.04%, 10=0.11%, 20=0.02%, 50=0.02%
      lat (msec)   : 100=0.05%, 250=0.07%, 500=0.01%
      cpu          : usr=1.41%, sys=1.52%, ctx=397, majf=0, minf=13
      IO depths    : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
         submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
         complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
         issued rwts: total=25600,0,0,0 short=0,0,0,0 dropped=0,0,0,0
         latency   : target=0, window=0, percentile=100.00%, depth=1
    write-and-verify: (groupid=0, jobs=1): err= 0: pid=9636: Wed Mar 24 17:50:32 2021
      read: IOPS=363, BW=1455KiB/s (1490kB/s)(100MiB/70368msec)
        slat (usec): min=2, max=4401, avg=46.08, stdev=38.17
        clat (usec): min=101, max=1002.5k, avg=43920.61, stdev=49423.03
         lat (usec): min=106, max=1002.5k, avg=43967.49, stdev=49419.62
        clat percentiles (usec):
         |  1.00th=[   188],  5.00th=[   273], 10.00th=[   383], 20.00th=[  3752],
         | 30.00th=[  8586], 40.00th=[ 16319], 50.00th=[ 28967], 60.00th=[ 45351],
         | 70.00th=[ 62129], 80.00th=[ 80217], 90.00th=[106431], 95.00th=[129500],
         | 99.00th=[181404], 99.50th=[200279], 99.90th=[308282], 99.95th=[884999],
         | 99.99th=[943719]
      write: IOPS=199, BW=796KiB/s (815kB/s)(100MiB/128642msec); 0 zone resets
        slat (usec): min=4, max=136984, avg=101.20, stdev=2123.50
        clat (usec): min=561, max=1314.6k, avg=80287.04, stdev=105685.87
         lat (usec): min=574, max=1314.7k, avg=80388.86, stdev=105724.12
        clat percentiles (msec):
         |  1.00th=[    3],  5.00th=[    5], 10.00th=[    6], 20.00th=[    7],
         | 30.00th=[   12], 40.00th=[   45], 50.00th=[   51], 60.00th=[   68],
         | 70.00th=[  111], 80.00th=[  136], 90.00th=[  167], 95.00th=[  207],
         | 99.00th=[  460], 99.50th=[  600], 99.90th=[ 1250], 99.95th=[ 1318],
         | 99.99th=[ 1318]
       bw (  KiB/s): min=  104, max= 1576, per=100.00%, avg=822.39, stdev=297.05, samples=249
       iops        : min=   26, max=  394, avg=205.57, stdev=74.29, samples=249
      lat (usec)   : 250=1.95%, 500=4.63%, 750=0.69%, 1000=0.40%
      lat (msec)   : 2=1.15%, 4=3.47%, 10=18.34%, 20=7.79%, 50=17.56%
      lat (msec)   : 100=20.45%, 250=21.82%, 500=1.27%, 750=0.23%, 1000=0.10%
      cpu          : usr=0.60%, sys=1.79%, ctx=46722, majf=0, minf=627
      IO depths    : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=99.9%, 32=0.0%, >=64=0.0%
         submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
         complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.1%, 32=0.0%, 64=0.0%, >=64=0.0%
         issued rwts: total=25600,25600,0,0 short=0,0,0,0 dropped=0,0,0,0
         latency   : target=0, window=0, percentile=100.00%, depth=16

    Run status group 0 (all jobs):
       READ: bw=2910KiB/s (2980kB/s), 1455KiB/s-21.7MiB/s (1490kB/s-22.7MB/s), io=200MiB (210MB), run=4612-70368msec
      WRITE: bw=796KiB/s (815kB/s), 796KiB/s-796KiB/s (815kB/s-815kB/s), io=100MiB (105MB), run=128642-128642msec

    Disk stats (read/write):
        dm-48: ios=26004/27330, merge=0/0, ticks=1132284/2233896, in_queue=3366684, util=100.00%, aggrios=28026/41435, aggrmerge=0/0, aggrticks=1292636/3986932, aggrin_queue=5288484, aggrutil=100.00%
        dm-56: ios=28026/41435, merge=0/0, ticks=1292636/3986932, in_queue=5288484, util=100.00%, aggrios=28027/41436, aggrmerge=0/0, aggrticks=0/0, aggrin_queue=0, aggrutil=0.00%
        md125: ios=28027/41436, merge=0/0, ticks=0/0, in_queue=0, util=0.00%, aggrios=13768/36599, aggrmerge=220/4980, aggrticks=622303/1259843, aggrin_queue=859540, aggrutil=61.10%
      sdb: ios=13271/36574, merge=193/5009, ticks=703823/1612782, in_queue=1077576, util=61.10%
      sda: ios=14265/36624, merge=248/4951, ticks=540784/906905, in_queue=641504, util=51.08%

Keep in mind the machine was not idle at the time of testing, quite
the contrary (under about 4-5 load).

## Glossary

 * **[SAN][]**: storage area network
 * **[iSCSI](https://en.wikipedia.org/wiki/ISCSI)**: SCSI over "internet", allows block devices to be
   mounted over TCP/IP
 * **iSCSI initiator**: an iSCSI "client"
 * **iSCSI target**: an iSCSI "server", typically a SAN with redundant
   disks, exposing block devices to iSCSI initiators
 * **multipath**: "a technique whereby there is more than one physical
   path between the server and the storage", typically this means
   multiple network interfaces on the initiator, target, running over
   distinct network switches (or at least VLANs)

[SAN]: https://en.wikipedia.org/wiki/Storage_area_network

## Network topoloy

The network at Cymru is split into different VLANs:

 * "public": VLAN 82 - 38.229.82.0/24, directly on the internet
   (behind the cymru router), `eth0` on all nodes.

 * "storage": VLAN 801 - 172.30.130.0/24. access to the iSCSI servers
   and also used by Ganeti and DRBD for inter-node communications. not
   directly accessible by the router, `eth1` on all nodes.

 * "management": VLAN 802 - 172.30.140.0/24, access to the iDRACs and
   IPMI management interfaces, not directly accessible by the router,
   but accessible from `eth2` on all the nodes but normally not
   configured.

This is summarized by this diagram:

![network topology graph](new-machine-cymru/topology.png)

Note that the `bastion host` configured above is not currently
configured: it can be configured by hand on one of the `chi-node-X`
machines since they have access to VLAN 802, but this should
eventually be fixed.

# Discussion

## Disabling the builtin RAID controller

We tried to disable the built-in RAID controller in order to use
software RAID. Hardware RAID is always a headache as it requires
proprietary drivers that are hard or impossible to find. By using
software RAID, we have the same uniform interface on all servers.

To disable hardware RAID on Cymru hardware (PowerEdge R610 or R620
machines), you have access to the BIOS. This can be done through a
Virtual console or serial port, if Serial redirection is first enabled
in the BIOS (which requires a virtual console). Then:

 1. reboot the server to get into the BIOS dialogs
 2. let the BIOS do its thing and wait for the controller to start
    initializing
 3. hit <kbd>control-r</kbd> when the controller dialog shows up

This will bring you in the RAID controller interface, which should
have a title like:

          PERC H710P Mini BIOS Configuration Utility 4.03-0002

WARNING: the following steps will destroy all the data on the disks!!

In the `VD Mgmt` tab:

 1. press <kbd>F2</kbd> ("operations")
 2. select "Clear Config" and confirm

Another way to do this is to:

 1. select the "virtual disk"
 2. press <kbd>F2</kbd> ("operations")
 3. choose "Delete VD" and confirm

```
press <Control-R>: to enter configuration utility
```

For good measure, it seems you can also disable the controller
completely in the `Ctrl Mgmt` tab (accessed by pressing
<kbd>control-n</kbd> twice), by unticking the `Enable controller BIOS`
and `Enable BIOS Stop on Error`.

To exit the controller, hit <kbd>Esc</kbd> ("Escape"). Then you need
to send <kbd>control-alt-delete</kbd> somehow. This can be done in the
`Macros` menu in the virtual console, or, in the serial console,
exiting with <kbd>control-backslash</kbd> and then issuing the command:

    racadm serveraction powercycle

Unfortunately, when the controller is disabled, the disks just do not
show up at all. We haven't been able to bypass the controller so those
instructions are left only as future reference.

For systems equipped with the *PERC H740P Mini* controller (eg.
`chi-node-14`), it's possible to switch it to "Enhanced HBA" mode
using the iDrac interface (requires reboot). This mode allows the
individual disks to be seen by the operating system, allowing the
possibility to use software RAID.

See also [howto/raid](howto/raid).

## Design

### Storage

The iSCSI cluster provides roughly 172TiB of storage in the management
network, at least in theory. Debian used this in the past with ganeti,
but that involves creating, resizing, and destroying volumes by hand
before/after creating, and destroying VMs. While that is not ideal, it
is the first step in getting this infrastructure used.

We also use the "normal" DRBD setup with the local SAS disks available
on the servers. This is used for the primary disks for Ganeti
instances, but provides limited disk space (~350GiB per node) so it
should be used sparingly.

Another alternative that was considered is to use [CLVM](https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/logical_volume_manager_administration/lvm_cluster_overview) ("The
Clustered Logical Volume Manager") which makes it possible to run LVM
on top of shared SAN devices like this. This approach was discarded
for a few reasons:

 1. it's unclear whether CLVM is correctly packaged in Debian
 2. we are not familiar with this approach at all, which requires us
    to get familiar *both* with iSCSI and CLVM (we already will need
    to learn the former), and this might be used only for this PoP
 3. it's unclear whether CLVM is production ready

We also investigated whether [Ceph][] could use iSCSI backends. It
does not: it can provide an iSCSI "target" (a storage server) but it
can't be an iSCSI "initiator". We did consider using Ceph instead of
DRBD for the SAS disks, but decided against it to save research time
in the cluster setup.

[Ceph]: https://en.wikipedia.org/wiki/Ceph_(software)

### multipath configuration

We have tested this `multipath.conf` [from Gabriel Beaver](https://gabrielbeaver.me/2013/03/centos-6-x-and-dell-md3000i-setup-guide/) and
[proxmox](https://pve.proxmox.com/wiki/ISCSI_Multipath#Dell) on `chi-node-01`:

```
# from https://pve.proxmox.com/wiki/ISCSI_Multipath#Dell
defaults {
  polling_interval        2
  path_selector           "round-robin 0"
  path_grouping_policy    multibus
  rr_min_io               100
  failback                immediate
  no_path_retry           queue
}

devices {
  # from https://pve.proxmox.com/wiki/ISCSI_Multipath#Dell
  device {
    vendor                  "DELL"
    product                 "MD32xxi"
    path_grouping_policy    group_by_prio
    prio                    rdac
    path_checker            rdac
    path_selector           "round-robin 0"
    hardware_handler        "1 rdac"
    failback                immediate
    features                "2 pg_init_retries 50"
    no_path_retry           30
    rr_min_io               100
  }
  device {
    vendor                          "SCST_FIO|SCST_BIO"
    product                         "*"
    path_selector                   "round-robin 0"
    path_grouping_policy            multibus
    rr_min_io                       100
  }
}

# from https://gabrielbeaver.me/2013/03/centos-6-x-and-dell-md3000i-setup-guide/
# Gabriel Beaver 03/27/2013
blacklist {
  devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
  devnode "^hd[a-z]"
  devnode "^sda"
  devnode "^sda[0-9]"
  device {
    vendor DELL
    product "PERC|Universal|Virtual"
  }
}
# END GB
```

It seems that configuration is actually optional: multipath will still
work fine without it, so it's not deployed consistently across nodes
at the moment.

### Ganeti iSCSI integration

See [Ganeti storage reference](howto/ganeti#storage) and [Ganeti iSCSI integration](howto/ganeti#iscsi-integration).

### Private network access considerations

We considered a few ideas to provide access to the management network:

 - OpenVPN
 - IPsec
 - SSH SOCKS proxying
 - sshuttle

We somehow expected cymru to provide us with a jump host for this
purpose, like they did with peninsulare for the `moly` server, but
this turned out to not happen.

We never really considered OpenVPN seriously: we already use ipsec
elsewhere and it seemed like a bad idea to introduce another
VPN technology when we were already using another one. This meant more
struggles with IPsec, but that, in turn, meant the staff gets more
familiar with it. In other words, if IPsec doesn't work, let's get rid
of it everywhere, and not make a special case here.

SSH SOCKS proxying (`-D`) was the idea of using one of the jump hosts
as an SSH proxy. It kind of worked: web browsers were able to access
the iDRAC web interfaces by manually configured a SOCKS5 proxy in the
settings (at least in Firefox). But that, in turn, did not necessarily
work across virtual machine boundaries (so that the Java stuff
worked), let alone insite the Java JVM itself. So this approach was
never seriously considered either, although it worked for the web UI.

sshuttle could have worked as well: it does provide routing somewhat
elegantly. Apart from the concerns established in the OpenVPN option
above (yet another VPN solution), it added the problem that it needs
to run as root on the client side. That makes it difficult to access
regular `ssh-agent` credentials (e.g. using a Yubikey). There are ways
to use `ssh -A root@localhost` to forward agent credentials, but that
seemed to hacky.

### VLAN allocations

The VLAN allocations described in the network topology above were
suggested by Cymru and slightly modified to fit our use case. See
[issue 40097](https://gitlab.torproject.org/tpo/tpa/team/-/issues/40097) for the gory details of that discussion.

There is flexibility upstream on VLAN allocation and possibly bundling
network interfaces together. All hosts have 8 interfaces so there's
lots of potential there.

It would be possible, for example, to segregate DRBD, iSCSI and Ganeti
traffic in *three* different VLANs. For now, we've adopted the path of
simplicity and all those live in the same private VLAN.
