I've swapped drives, expanded and shrinked array before while I had all xfs formated drives and no pool except cache pool so I know how it goes in that case and it's as simple as New config with Preserve current assignments, shuffle the config, add drives, remove drives, etc. and voilà. Magic happens over night with minimal input from my part...

Now I'm using a both array and a zfs pool and I'm not sure how it goes in this case.

This is what I have right now:

Array:

parity (sdb)

disks 1-2-3 (sdi,sdd,sdc) as xfs

and disk 4 (sde) as zfs

Pool:

3 disks as ZFS (sdf, sdg, sdh):

I want to remove disks 2, 3 and 4 from the array. I've already moved all the data to disk 1 (sdi) in array. I understand parity will have to be rebuilt, not a problem, data from array is duplicated on a spare NAS while parity rebuild happens, just in case. I do not have enough HDD space to duplicate data from zfs pool though so I'm wondering.

1. If stop the array and do "New Configuration>Preserve current assignments", remove disks 2,3,4 from array and pull them out of the machine will zfs pool be affected since sdd, sdc and sde disks will no longer be in the server?

2. Do I have to do anything at all, like importing zfs pool or similar (I've no aidea how to do it), or is it all automatic like it was before when I did it with no pool and only xfs array?

Edited September 22, 2025Sep 22 by Lavoslav
SOLVED

Keep all assignments when doing the new config, remove the devices you want from the array, leave the pool assignments intact, and it should be reimported at array start.

Everything went without any issues.

Since I rarelywent above 15ish % CPU usage at max when working it "hard", usually it was at arround at 3-7%, I also swapped from custom built i9-13900k to a Lenovo P520 with Xeon W-2223. Beefed up to 80Gb ECC RAM too. UnRaid did not care at all about the hardware swap. Booted on 1st attempt.