Hi,

I've had my UnRAID running for a few years, on an old Mac Mini 2012 with a USB3.0 5-bay JBOD enclosure. My setup was 8TB parity, 2x 8TB and 2x 4TB data drives, for a total of 24TB parity-protected.

My server mysteriously vanished from the network a few days and and a reboot seemed to resolve things, but it went down again and nothing would seem to bring it back. I also heard ominous noises from the disk array...

The USB key also appears to have become corrupted, I checked it for errors, it seemed ok, so I formatted it and reinstalled UnRAID via the installer tool, and recovered my key. The server seems happy now, with the Plus license showing. However, booting with the drive array connected was not possible.

In short, it appears one of my 8TB data drives is kaput - mounting it on my Mac via 'anylinuxfs' results in:

```
rory@Zaphod ~> sudo anylinuxfs mount /dev/disk38s1

Password:

Linux: mount: /mnt/disk38s1: wrong fs type, bad option, bad superblock on /dev/vda, missing codepage or helper program, or other error.

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

macOS: root_path: /Users/rory/.anylinuxfs/alpine/rootfs
```

So I have a blank / unconfigured UnRAID server, existing disks to add to it, and a dead disk in need of replacement. I'm not totally sure I can afford an 8TB drive right now, so wondering what my options are. I think to rebuild from parity, i'd definitely need a replacement 8TB drive for the dead one, but how realistic is it I can restore the setup such that it will recover from parity? I backed up the 'config' folder from the USB key before reformatting it, thinking that it would restore if i copied it back to the USB key but this does not seem to have been the case.

Any help or advice would be greatly appreciated!

Start array in normal mode and

Attach Diagnostics ZIP to your NEXT post in this thread.

Not sure how I can start the array - there are no drives assigned to it so far. If I add the 'good' remaining drives, should I just omit the dead / missing one? I.e. leave a blank slot?

Edited September 17, 2025Sep 17 by tehmungler

titanic-diagnostics-20250917-1145.zip

Just booted up with the dead disk removed from the JBOD, no disks assigned so far.

Thanks for any help / guidance from this point.

It would be good to see SMART for the dead drive, but you can create a new array with the remaining drives. If you don't know which drive was parity, see here:

https://docs.unraid.net/unraid-os/system-administration/maintain-and-update/changing-the-flash-device/#recovering-from-a-failed-flash-device-without-a-backup

Thanks @JorgeB - if I assign the same drives as before, and get the parity disk right, will it automatically emulate the missing drive? Or should I connect the 'bad' drive and add that (assuming the OS recognises it at all)?

2 hours ago, tehmungler said:

if I assign the same drives as before, and get the parity disk right, will it automatically emulate the missing drive?

Nope, you can try this, but need a new spare drive:

-Tools -> New Config -> Retain current configuration: All -> Apply

-Check all assignments and assign any missing disk(s) if needed, including the new disk you want to rebuild, replacement disk should be same size or larger than the old one

-IMPORTANT - Check both "parity is already valid" and "maintenance mode" and start the array (note that the GUI will still show that data on parity disk(s) will be overwritten, this is normal as it doesn't account for the checkbox, but it won't be as long as it's checked)

-Stop array

-Unassign the disk you want to rebuild

-Start array (in normal mode now), and post new diagnostics

Ok, thanks. I'm not really in the financial league to add a new 8TB drive at present, but would like to recover a few hundred GB of data that I can't replace from the array. The rest can be replaced easily enough by downloading it all again.

Is there a way to set up UnRAID to emulate the damaged disk such that I can get a read-only view of the array as-was?

Actually, i'm in luck. Turns out it was the parity disk that died, so i've been able to start the array 'unprotected' without parity, and will move my valuable data to other storage before rebuilding my UnRAID server. Thanks all.