Seems like it's my turn to bork something up, and worse yet, be swamped at work so little time for looking into what's happened (hence the almost three-month-old diagnostics).

I had an old, slow HDD that I figured was up for replacement - I replaced it with a (very) occasionally flaky new, larger drive (which was dumb, but I figured it was a connector issue, not a drive issue). At first, it worked OK, until the drive dropped out of the array. Then it got rebuilt onto itself, and I can't remember if it worked OK again, or if it crapped out before that and wound up dropped again. Either way, I ran a few more cycles of preclear on the drive, rebuilt it, and the drive wound up dropping out of the array again once it was back up running, so I replaced that drive with a second new drive (presumed good, freshly bought - it did three passes of preclear with zero issues, and S.M.A.R.T testing was OK as well), rebuilt the array onto the second new drive, and the second new drive is now exhibiting the same problem - it drops out of the array and gets emulated quite quickly.

TL;DR: Changed old small drive to a bigger HDD, bigger HDD gets dropped from the array some time after starting it, test bigger HDD with 3x preclear which is OK, rebuilt bigger HDD onto itself, drops out of array quite quickly, test x3 and rebuild same story, replace bigger drive with new drive, pre-cleared x3 with no issues, now new drive is dropping out of the array as unmountable. At skill limit for diagnosis. Connectors have been switched around, with no changes noted.

I think the diagnostics are from one of the first times it happened with the new drive.

Edited June 26Jun 26 by Vcent

How is that DVD drive connected?

SATA to motherboard.

It was spamming syslog in those diagnostics. Do you still have the problem if you disconnect that?

I've disconnected it, but the drive is still shown as disabled/emulated/unmountable, even after a reboot.

I must admit I'm blanking a bit on the correct procedure to bring it back online - maintenance mode -> drive properties -> BTFRS check --readonly gives an error suggesting corruption (expected XXXX found YYYYY, and then fails to open the filesystem as it can't be found).

*Exact output was :

parent transid verify failed on 3350031482880 wanted 502589 found 502438
parent transid verify failed on 3350031482880 wanted 502589 found 502438
parent transid verify failed on 3350031482880 wanted 502589 found 502438
Ignoring transid failure
ERROR: child eb corrupted: parent bytenr=3350034989056 item=190 parent level=1 child bytenr=3350031482880 child level=1
ERROR: failed to read block groups: Input/output error
ERROR: cannot open file system
Opening filesystem to check...

Edited June 20Jun 20 by Vcent
Update/Addition/Correction

Previous diags are full of spam, post new ones please without the DVD drive (after array start)

My apologies.

Edited June 26Jun 26 by Vcent

Emulated disk5 has filesystem issues, and with btrfs this may not be an easy fix, my first suggestion would be see it the actual disk can mount with the UD plugin (you need to unassign it first), also keep the old disk instact for now if you still have it.

It would appear that the answer to that question is no, it can't mount with the UD plugin.

Edited June 26Jun 26 by Vcent

Actual disk also has filesystem issues, you can try the recovery options here: https://forums.unraid.net/topic/46802-faq-for-unraid-v6/page/2/#findComment-543490

Since the problem is the same, they could be used with the actual disk or the emulated one

I'm having a hard time figuring out if I've done it correctly - attempting to mount it with mount -o rescue=all,ro /dev/mapper/sdf1 /temp

results in

>mount: /temp: special device /dev/mapper/sdf1 does not exist.

dmesg(1) may have more information after failed mount system call.

Which seems reasonable enough (the drive was unassigned after all).

mount -o rescue=all,ro /dev/sdf1 /temp

Gets

>mount: /temp: unknown filesystem type 'crypto_LUKS'.

dmesg(1) may have more information after failed mount system call

Which also seems reasonable enough, since the drive is encrypted.

Hunting for a different mountpoint with df -h and btfrs fi show found me /dev/mapper/m5p1, which does indeed match the missing disk in size and used amount, and will allow itself to mount to /temp quite happily - and it does contain data.

Since the drive is encrypted, you need to decrypt it first, one of the reasons I don't recommend encryption unless absolutely necessary; it just complicates things, assuming you are using a keyfile and it's loaded:

cryptsetup luksOpen /dev/sdf1 sdf1 --key-file=/root/keyfile

Yeah, I'm learning that now.

Mounted perfectly fine, once I remembered to point towards the mapper.

Is the next step to move the data and nuke the drive?

If it only mounted read only, yes, you will need to copy the data someplace else and then reformat.

Pretty sure everything has been copied, and I do still have the original drives.

That being said, I am being told multiple, somewhat conflicting things by unraid by now (I've re-added the drive to the array, got the blue dot, started the array/rebuild).

Unraid is simultaneously telling me that there's an unmountable disk present (disk 6 now, for some reason), and that it's doing a data rebuild.

Unassigned devices is showing the problematic disk, and no writes are being noted by either UD or the array GUI (It's just reading the working disks, writing is a solid 0.0B/s, and disk 5 is shown with the yellow warning triangle denoting an emulated disk).

I'm unsure if this is unraid being cryptic, and if it's working as intended, or if it's failing.

Edit: and I'm getting a boatload of errors from drive 6 now, zero correct reads. Paused the rebuild so far.

tower-diagnostics-20260626-0617.zip

Edited June 26Jun 26 by Vcent
Boatload of trouble, apparently.

2 hours ago, Vcent said:

Unraid is simultaneously telling me that there's an unmountable disk present (disk 6 now, for some reason), and that it's doing a data rebuild.

This is normal; they are two different things, if all the data has been copied, you can format the disk, then restore the data (restore part is better done after the rebuild finishes).

2 hours ago, Vcent said:

Edit: and I'm getting a boatload of errors from drive 6 now, zero correct reads. Paused the rebuild so far.

Looks more like a power/connection issue. Check/replace cables, also, any power splitters in use?

Disk6 disconnected as sdc and is now unassigned device sdj

6 hours ago, JorgeB said:

Looks more like a power/connection issue. Check/replace cables, also, any power splitters in use?