Currently appdata is all on cache. It is configured to write new files to cache.

Don't see any evidence that any data was lost. Same amount of data as in your first diagnostics in this thread. And more data than you had in the diagnostics from your thread in December. Those diagnostics do show some appdata on disk2.

https://forums.unraid.net/topic/195930-zfs-pool-unmountable-after-reboot/

On 4/27/2026 at 9:38 AM, lbrwnie said:

Roger, will fix this up. Had a ZFS pool fail a while ago and swapped these around, must have forgot to fix it.

domains and system are still on the array. They won't be moved because they have no Mover action because they have no Secondary. And as mentioned, nothing can move open files.

1 hour ago, trurl said:

Disk2 and what other disk?

Disk 5

54 minutes ago, trurl said:

Currently appdata is all on cache. It is configured to write new files to cache.

Don't see any evidence that any data was lost. Same amount of data as in your first diagnostics in this thread. And more data than you had in the diagnostics from your thread in December. Those diagnostics do show some appdata on disk2.

https://forums.unraid.net/topic/195930-zfs-pool-unmountable-after-reboot/

domains and system are still on the array. They won't be moved because they have no Mover action because they have no Secondary. And as mentioned, nothing can move open files.

My UI says 21.5TB used on the array right now. Could you confirm if the usage is different on any of those diags? Planning on moving domains and system once I have this parity operation complete

1 hour ago, trurl said:

Currently appdata is all on cache. It is configured to write new files to cache.

Don't see any evidence that any data was lost. Same amount of data as in your first diagnostics in this thread. And more data than you had in the diagnostics from your thread in December. Those diagnostics do show some appdata on disk2.

https://forums.unraid.net/topic/195930-zfs-pool-unmountable-after-reboot/

domains and system are still on the array. They won't be moved because they have no Mover action because they have no Secondary. And as mentioned, nothing can move open files.

Here is comparison from the first set of diags to now

Definite data loss on disk 2 and 5. That's including some 500GB+ I have been slowly re-downloading from backup for one of my shares.

xfs_repair losing so much data suggests there were serious file system issues with the disks, e.g, like if parity wasn't 100% valid for disk2, was the other disk also disabled or rebuilt?

Sorry, you are correct about the previous and now. I misread the diagnostics.

22 minutes ago, JorgeB said:

if parity wasn't 100% valid for disk2, was the other disk also disabled or rebuilt?

Or did you perhaps New Config at some point? Any data written to the disk(s) while they were emulated would be lost with New Config.

8 hours ago, JorgeB said:

xfs_repair losing so much data suggests there were serious file system issues with the disks, e.g, like if parity wasn't 100% valid for disk2, was the other disk also disabled or rebuilt?

I did replace disk 5 from 4tb to 8tb recently.

7 hours ago, trurl said:

Sorry, you are correct about the previous and now. I misread the diagnostics.

Or did you perhaps New Config at some point? Any data written to the disk(s) while they were emulated would be lost with New Config.

Not as far as I know, only just read up on that now you mentioned it. I was just doing the old way of replacing/rebuilding drives up to now.

I understand its a weird one. Just want to make sure this won't happen much again, appreciate all your help looking into this

1 hour ago, lbrwnie said:

I did replace disk 5 from 4tb to 8tb recently.

Did you let it completely rebuild the whole 8TB when you did this?

51 minutes ago, trurl said:

Did you let it completely rebuild the whole 8TB when you did this?

Ya, the UI showed it as complete. This is an unraid install that has been around almost 10 years now, first time running repair on the array. Could just be never run it before and had a lot of error correction to do?

Should be fine with my backup but offsite limited to 20Mbps upload so taking a while to pull it back down again haha

1 hour ago, trurl said:

Did you let it completely rebuild the whole 8TB when you did this?

Actually also found a lost+found folder in /user/lost+found but when navigating via GUI is just gets stuck loading

5 minutes ago, lbrwnie said:

Actually also found a lost+found folder in /user/lost+found but when navigating via GUI is just gets stuck loading

Got a bunch of this using ls command in terminal after about 10mins of waiting

Did you run regular parity checks, and were they always clean?

2 hours ago, JorgeB said:

Did you run regular parity checks, and were they always clean?

Yeah monthly checks, clean as far as I remember

Something likely happened to result in large corruptions, but it's difficult to guess exactly why without logs that cover events since the last parity check until now.

Just now, JorgeB said:

Something likely happened to result in large corruptions, but it's difficult to guess exactly why without logs that cover events since the last parity check until now.

Fair enough, thought it would be something like that. Appreciate your assistance with this. Haven't had the USB drive error pop back up. Fingers crossed the whole thing is fixed up now, will also be swapping out my old HBA and cables for a new one in case that was causing the issues with the drives becoming disabled without actually having any issues.