Feedback about iSCSI High Availability Clustering Using DRBD and Pacemaker on RHEL 9

[Strahil Nikolov]

Hi All,
Do we have a thread about the HA iSCSI article ?I saw a few things that can be optimized/updated:


1. Point 3.7.1 Shouldn't be done as pcs has a native way to auth, assemble and start the cluster and corosync tinkering is no longer needed. Something like this:
echo 'somepass' | passwd --stdin haclusterpcs host auth node1 node1.example.com node2 node2.example.com 
pcs cluster setup CLUSTERNAME node1 node2 totem token=10000 --enable --start

2. Point 3.8 is against any high availability and against Red Hat support policy - it should have a red lavel that this is done for the demo !
3. In point 3.10 I highly recommend setting scsi_sn for the ocf:heartbeat:iSCSILogicalUnit - the software by default picks the same SN for the first LUN and when 1 client attaches 2 LUNs (from 2 srparate clusters) multipath will treat the 2 sources as one and aggregate the paths - becomes a real mess
4. Consider LVM filter for the DRBD device - a client might use the LUN as a PV in a volume group and then thr situation will get messy - the cluster won't be able to demote the node and pacemaker will fence it.
5. Consider using fencing delay when using 2-node clusters - in case of split brain scenario the node with more resources will survive:
pcs resource defaults update priority=1pcs property set priority-fencing-delay=10

Best Regards,Strahil Nikolov
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