ZFS Pools, Physical Disk Location and Boot Mirror

I think I’m correct in saying that TNS and ZFS utilises disk IDs, rather than device names, for vdev/pool membership, right? So, in theory, I could shut the server down, shuffle the disks into new slots, boot up and all the vdevs, pools and datasets would be fine.

However, I note that when I run ‘zpool status’ from the command-line, my mirror-0 boot pool is listed using device names (in my case sda and sdb).

Is this because the system has to boot off /dev/sda before it’s started the ZFS service, and it only becomes mirrored (and, I guess, read/write) once it’s booted far enough to run ZFS?

Would I also be correct on thinking that, as this zpool is defined using device names, I cannot physically move those disks? (Well, I could, but it would break things)

I’ve stuck labels on those two disk caddies for now so I know what they are and where they should be located.


Also correct. Someone made a bit of a stink about this in the release topic for SCALE 24.04; prior to that I can’t remember seeing it mentioned (and FreeNAS/TrueNAS has been using ZFS for the boot device for 10 years now).

That would make logical sense, though I’m not sure it’s been demonstrated as yet.


Thanks, Dan. I’ll take a “better to be safe than sorry” approach with this, then.