@dinhngtu Yeah, I suspected that as well. So I inspected the SR and it showed connected to both hosts (at least in the XO UI - I didn't drop to the CLI to really confirm).
By altering my workflow a bit and slowing down, I seem to have found the right "sweet spot" of delay and the issue hasn't resurfaced. Here's what I'm doing now, when I need to revert the snapshots of all three VMs:
In the XO VM list, I select the three VMs and power them off at the same time.
I then start with VM1 and eject the ISO, VM2 and eject the ISO, then VM3 and eject the ISO. By the time I circle back to VM1 for the next step, about 10-15 secs have elapsed.
I then start with VM1 and revert the snapshot, and repeat the same on VM2 and VM3. By the time I circle back to VM1 for the next step, another 10-15 secs have elapsed.
I re-attach the ISO to all three VMs in sequence. Another 10-15 secs elapse.
I then start with VM1 and power all three VMs sequentially.
The entire workflow takes about 30-45 secs, and I'm finding that by doing this, the issue hasn't resurfaced.