What are you guys using for your vm disk format when running zfs as main filesystem?
Do I just need to use raw and setup a dataset for each vm for best performance or is it ok to use qcow2 on top of zfs?
I recall seeing a comparison out there in the wild that examined the differences between various virtual disk formats on top of various file systems. IIRC, qcow2 on top of ZFS came out on top. One way or another, that's what I've ended up using for myself and for several deployments for small businesses I have floating around my city. If better performance is ever necessary, I'll look into moving from RAIDZ2 to a pool of mirrors. VM disk format couldn't be further from the front of my mind.