expand on host groups creation

howto/new-machine-cymru.md

@@ -223,6 +223,16 @@ 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 iscsiName="iqn.1993-08.org.debian:01:chi-node-04" userLabel="chi-node-0X-iscsi" host="chi-node-0X";
+
+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
@@ -765,21 +775,43 @@ Details (like speed in RPMs) can also be seen with:
 
 ### Adding a host
 
-Create a host group, a host inside it, and its matching iSCSI initiator:
+The existing machines in the `gnt-chi` cluster were all added at once,
+alongside a group, with this script:
 
-    create hostGroup userLabel="stor01-raid10-1";
-    create host userLabel="chi-node-01" hostType=1 hostGroup="stor01-raid10-1";
-    create iscsiInitiator iscsiName="iqn.2005-03.org.open-iscsi:c1ec2e02a4a" userLabel="chi-node-01-iscsi" host="chi-node-01";
+    show "Creating Host Group gnt-chi.";
+    create hostGroup userLabel="gnt-chi";
 
-Only the last two lines are necessary if the group already exists, naturally.
+    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";
 
-To find the right iSCSI initiator identifier, you need to run this
-command on the host:
+    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";
 
-    iscsiadm -m session -P 1 | grep 'Iface Initiatorname' | sort -u 
+For new machines, only this should be necessary:
 
-Note that this setting is also visible in
-`/etc/iscsi/initiatorname.iscsi`, where it can be changed as well.
+    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 
 
 ### Creating a disk