Hi, I have a simple oVirt setup, with one storage server and a couple of hypervisors, running some 50 VMs. The storage server uses ZFS zvols, exported over iSCSI with SCST. Now I want to do some maintenance on the storage, specificly I want to update SCST to a new version. I expect that the normal procedure for this would be: - shutdown all VMs - put storage domain into maintenance - perform maintenance - get everything back online Now I know I can also take the following ugly shortcut: - stop SCST daemon - see all VMs go to Paused - perform maintenance - restart SCST - resume all VMs or wait for them to resume themselves The win being of course, that nothing has to be restarted/rebooted. Extremely small scale testing (one running VM on a 20 GB test domain) indicates, that this works like a charm. The VM resumes without a problem and doesn't log anything storage related. My question is: what are the risks involved in the shortcut scenario? I understand that there are IOPS that never reach the disk, so they have to be queued somewhere (inside Qemu I presume). What happens if this happens with 50 VMs at once? Best regards, Martijn.