JorgeB

Sorry, meant -l, but it confirms there's GPT corruption, you can usually fix that with gdisk, use gdisk with each data disk: gdisk /dev/sdX Will should also detected the corrupt GPT and if you type w it will write the corrections, the try to start array again.

Better would be to have a second server as a backup, but you can also use some drives with the UD plugin to backup some or all your data, you'd need to use scripts with rsync or similar.

Those errors are quiet common, see them in many diags.

Yes, looks like the same controller issue.

This usually means something is interruption the SMART test.

SATA controller is bound to vfio-pci, unbind it, also make sure you update to latest release.

The current Asmedia controllers you're using are generally fine, but if there are future disk issues grab diags before rebooting and post those.

Not that I'm aware of.

So which UD device is not mounting?

Looks like MBRs were changed/corrupted, any RAID controller involved in one or the other setup? Please post output of: fdisk -f /dev/sdX replace X with one of the data disks.

That's an old 3Ware controller, IIRC it worked but there were some performance issue, I would stick to one of the rerecorded controllers: https://forums.unraid.net/topic/102010-recommended-controllers-for-unraid-last-updated-022021/

It happened because the array was started with just a single device and there were already a lot of errors, likely from a pool device dropping offline previously, the balance didn't finish because of the errors or it was canceled, and when you added the second device back it was wiped, there would have been a warning in red "all data on this device will be deleted at array start". You can try this on the wiped device (sdb in the log): btrfs-select-super -s 1 /dev/sdX1 If the command is successful then make Unraid "forget" the pool by starting the array without any cache devices assigned, then stop array, re-assign only sdb and see if it mounts, if it does wipe sdc with blkdiscard and add it back to the pool, if it doesn't there are some recovery options here.

Which is it or did you have two identical devices? Log shows 3 UD devices: Feb 13 21:24:27 Arthur unassigned.devices: Disk with serial 'SanDisk_SDSSDP064G_140239400381', mountpoint 'SanDisk_SDSSDP064G_140239400381' is set as pass through Feb 13 21:24:27 Arthur unassigned.devices: Disk with serial 'WDC_WD40EZRZ-75GXCB0_WD-WCC7K1LTTRFL', mountpoint 'RECS' is set as pass through. Feb 13 21:24:27 Arthur unassigned.devices: Disk with serial 'WDC_WD80EZAZ-11TDBA0_1EGDL8EN', mountpoint 'WDC_WD80EZAZ-11TDBA0_1EGDL8EN' is not set to auto mount. Two are set as pass through so they can't be mounted by UD, the other one is set to not automount and I don't see any manual mount attempts.

Use -L

The one you're using is a good option, but it might be a fake or just some other problem/compatibility issue, for a list of recommended controllers see here:

If it's not RAM it can be a controller or even a hard drive, unfortunately no easy way to test except rule out one thing at a time.

sgd has issues, doesn't mean it's going to fail soon but it's not performing normally, also more likely that in time those slow sector will result in bad sectors, if you can return and get a new one I would.

You can't trim an SSD assigned to the array, trim is disable, on purpose I guess. As for the warning it's better to play on the safe side, but in my experience most SSDs should not cause any issues, the exception from the many I tested is the now discontinued Kingston V300, which caused a couple of sync errors after a power cycle, I would just recommend frequent parity checks, at least in the beginning, if no sync errors are found you're fine.

You'd need to do a new config, though if the RAID controller used non standard partitions Unraid will complain, usually that's not the case, and you can go back if needed.

Cache filesystem is corrupt, there are some recovery options here.

Start here: https://forums.unraid.net/topic/46802-faq-for-unraid-v6/?do=findComment&comment=819173

Please post the diagnostics: Tools -> Diagnostics

I have some N300 6TB, as well as the X300, good performance and no failures so far, I do find them a bit noisy though, rotation noise, not seek, if that's a problem.

Stop array, unassign parity2, start array.

Yep. Correct.