I have a 2-node CentOS7 cluster running ZFS. The two nodes (vsphere appliances on different hosts) access 2 SAS SSD in a Supermicro JBOD with 2 mini-SAS connectors. It all works fine - failover and all. My quandary was how to implement fencing. I was able to get both of the vmware SOAP and REST fencing agents to work - it just isn't reliable enough. If the vcenter server appliance is busy, fencing requests timeout. I know I can increase the timeouts, but in at least one test run, even a minute wasn't enough, and my concern is that too long switching over, and vmware will put the datastore in APD, hosing guests. I confirmed that both SSD work properly with the fence-scsi agent. Fencing the host who actively owns the ZFS pool also works perfectly (ZFS flushes data to the datastore every 5 seconds or so, so withdrawing the SCSI-3 persistent reservations causes a fatal write error to the pool, and setting the pool in failmode=panic will cause the fenced cluster node to reboot automatically.) The problem (maybe it isn't really one?) is that fencing the node that does *not* own the pool has no effect, since it holds no reservations on the devices in the pool.) I'd love to be sure this isn't an issue at all.
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