ZVOL Used Space

One of the more common complaints I hear about with ZFS is when clients are using zvol's to offer up iSCSI or FC block targets to clients, formatting filesystems on them, and then using them. Well, I don't get complaints about that, so much.. what I get are complaints about how, over time, the 'used' space as visible in ZFS is completely out of whack with the used space as visible in the filesystem on the client.

VM Disk Timeouts

A pretty common issue to run into when using some SAN back-ends for virtual machines is that the VM's end up crashing, BSOD'ing, or (most commonly) remounting their "disks" read-only when there's a hiccup or failover in the storage system, often resulting in a need to reboot to restore functionality.