I was attempting to move my array to ZFS. Initially, this went well.
I put in a new drive and replicated my data to the new single-drive ZFS pool with unbalance. Everything worked great. Added a 2nd drive with no issues. Ran this for a day as a sanity check with a 3rd drive on the side to be added when I felt comfortable with the changes.

When I added the 3rd to the zpool the array would not start. That's when I learned you can't go from mirrored to raidz1.... I tried to create a new pool since the array would not start. Now all the drives show as unmountable. Please help. Hopefully I did not nuke all of my data...

Tried adding in a 2nd new drive that I can safely format but the drive is DOA.

So current state:

Unraid Version: 7.2
Cache pool of 2 drives. Still ok
3 Unmountable drives formatted to ZFS
1 is blank 2 should still contain data.

Edited March 28Mar 28 by aasberry

Please post the diagnostics and the output from zpool import

I have been working on this and I think I am pretty close. zpool import did have two pools that were causing issues. I deleted one that was invalid. Recovered the other. But now I am a bit stuck.

The GUI says "unmountable: wrong or no file system". But I can mount the pool in the CLI just fine and see all of the data.

root@OneForAll:~# zfs list

NAME USED AVAIL REFER MOUNTPOINT

main 2.54T 993G 388K /mnt/main

main/Backups 7.79G 993G 7.38M /mnt/main/Backups

main/Backups/appdatabackup 6.82G 993G 6.82G /mnt/main/Backups/appdatabackup

main/Backups/flashdrive backup 992M 993G 992M /mnt/main/Backups/flashdrive backup

main/Backups/libvirt backup 480K 993G 480K /mnt/main/Backups/libvirt backup

main/CommunityApplicationsAppdataBackup 2.38G 993G 2.38G /mnt/main/CommunityApplicationsAppdataBackup

main/Downloads 152K 993G 152K /mnt/main/Downloads

main/Home 3.64G 993G 3.64G /mnt/main/Home

main/Media 2.29T 993G 18.2G /mnt/main/Media

main/Media/Books 155G 993G 155G /mnt/main/Media/Books

main/Media/Movies 1.24T 993G 1.24T /mnt/main/Media/Movies

main/Media/Music 120K 993G 120K /mnt/main/Media/Music

main/Media/Pictures 4.72G 993G 4.72G /mnt/main/Media/Pictures

main/Media/TV Shows 102G 993G 102G /mnt/main/Media/TV Shows

main/Media/audiobooks 801G 993G 801G /mnt/main/Media/audiobooks

main/NextCloud 241G 993G 241G /mnt/main/NextCloud

main/Software Repository 1.54G 993G 1.54G /mnt/main/Software Repository

main/isos 144K 993G 144K /mnt/main/isos

root@OneForAll:~# zpool status main

pool: main

state: ONLINE

scan: resilvered 2.55T in 05:31:25 with 0 errors on Sat Mar 28 13:45:24 2026

config:

NAME STATE READ WRITE CKSUM

main ONLINE 0 0 0

mirror-0 ONLINE 0 0 0

ata-ST4000VN008-2DR166_ZGY6TQ7V ONLINE 0 0 0

ata-WDC_WD40EFPX-68C6CN0_WD-WX12DA5AYFL5 ONLINE 0 0 0

errors: No known data errors

Here is the diagnostic file from my current state:
oneforall-diagnostics-20260328-1457.zip

For the main pool, try this:

First, it must be exported: zpool export main

Then with the array stopped, go to Main and click on the first device for that pool and then "remove pool"

back on main, create a new pool with the same name and number of slots

assign the pool devices, leave the filesystem set to auto

start the array to import the pool and post new diags if it fails.