howto/ganeti: update iSCSI instance creation (team#40734)

howto/ganeti.md

@@ -164,12 +164,12 @@ initiator properly setup](howto/new-machine-cymru#iscsi-initiator-setup), and th
 setup](howto/new-machine-cymru#san-management-tools-setup). It also assumes you are familiar with the `SMcli` tool, see
 the [storage servers documentation](howto/new-machine-cymru#storage-servers) for an introduction on that.
 
-This assumes you are creating a 500GB VM, partitioned on the Linux
-host, *not* on the iSCSI volume. TODO: change those instructions to
-create one volume per partition, so that those can be resized more
-easily. The following is how `tb-build-03` was setup.
+ 0. review the current storage allocation configuration
 
- 1. create the disk on the SAN and assign it to the host group:
+     /usr/local/sbin/tpo-show-san-disks
+
+ 1. create a dedicated disk group and virtual disk on the SAN and assign it to
+    the host group:
 
         puppet agent --disable "creating a SAN disk"
         $EDITOR /usr/local/sbin/tpo-create-san-disks
@@ -193,13 +193,13 @@ easily. The following is how `tb-build-03` was setup.
         }
 
  3. propagate the magic to all nodes in the cluster:
- 
+
         gnt-cluster command "puppet agent -t ; iscsiadm -m node --rescan ; multipath -r"
 
  4. confirm that multipath works, it should look something like this":
 
         root@chi-node-01:~# multipath -ll
-        web-chi-03-srv (36782bcb00063c6a500000d67603f7abf) dm-20 DELL,MD32xxi
+        test-01 (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
@@ -211,7 +211,7 @@ easily. The following is how `tb-build-03` was setup.
           `- 8:0:0:4  sdm 8:192 active ghost running
         root@chi-node-01:~#
 
-    and the device `/dev/mapper/web-chi-03` should exist.
+    and the device `/dev/mapper/test-01` should exist.
 
  6. adopt the disks in Ganeti:
 
@@ -222,28 +222,28 @@ easily. The following is how `tb-build-03` was setup.
               --net 0:ip=pool,network=gnt-chi-01 \
               --no-ip-check \
               --no-name-check \
-              --disk 0:adopt=/dev/disk/by-id/dm-name-tb-build-03-root \
-              --disk 1:adopt=/dev/disk/by-id/dm-name-tb-build-03-swap,name=swap \
-              --disk 2:adopt=/dev/disk/by-id/dm-name-tb-build-03-srv \
-              --backend-parameters memory=16g,vcpus=8 \
-              tb-build-03.torproject.org
+              --disk 0:adopt=/dev/disk/by-id/dm-name-web-chi-03 \
+              --backend-parameters memory=8g,vcpus=2 \
+              test-01.torproject.org
 
     NOTE: the actual node must be manually picked because the `hail`
     allocator doesn't seem to know about block devices.
 
+    NOTE: mixing DRBD and iSCSI volumes on a single instance is not supported.
+
  7. at this point, the VM probably doesn't boot, because for some
     reason the `gnt-instance-debootstrap` doesn't fire when disks are
     adopted. so you need to reinstall the machine, which involves
     stopping it first:
 
-        gnt-instance shutdown --timeout=0 tb-build-03
-        gnt-instance reinstall tb-build-03
+        gnt-instance shutdown --timeout=0 test-01
+        gnt-instance reinstall test-01
 
     HACK: the current installer fails on weird partionning errors, see
-    [upstream bug 13](https://github.com/ganeti/instance-debootstrap/issues/13). We applied [patch 14](https://github.com/ganeti/instance-debootstrap/pull/14) on `chi-node-04`
-    and sent it upstream for review before committing to maintaining
-    this in Debian or elsewhere. It should be tested on other installs
-    beforehand as well.
+    [upstream bug 13](https://github.com/ganeti/instance-debootstrap/issues/13).
+    We applied [patch 17](https://github.com/ganeti/instance-debootstrap/pull/17)
+    on `chi-node-01` and sent it upstream for review before committing to
+    maintaining this in Debian or elsewhere.
 
 From here on, follow the [next steps](#next-steps) above.