Hi!

I'm in a bit of a trouble. I had a short power disconnection in my house, leaving my unraid system without power.

It consists of a TerraMaster F-4 with 4 HDDs (1x12TB parity, 2x12TB plus 1x8TB data) and a TerraMaster D4-320 with 3x8TB data disks.

When booting up, one of the D4 disks got the alert "All existing data on this device will be OVERWRITTEN when array is Started"

I booted up several times, but the error persists.

Can someone please give me support to get this array online again? I really have no idea what to do in this situation. I attached my diagnostics.

Thank you soo much for helping out!
:(

EDIT:
When clicking the disks in the MAIN tab, all drives have the info "GPT: 4KiB-aligned", the one that gets the warning has "GPT: custom"!

terra-diagnostics-20250626-1521.zip

Edited June 26, 20251 yr by Gekko

Unassign disk6 then start the array in normal mode and post new diagnostics.

But what about the data on it? I am in full panic that this will destroy the array's integrity.

Are you really sure i should do this? Sorry, i'm really panicking right now.

Ok, i unassigned Dsik6 and started the array, then downloaded the new diagnositcs.

terra-diagnostics-20250626-1549.zip

We cannot see what happened since the diags are after rebooting, but the emulated disk6 is mounting and SMART looks fine, so most likely a power/connection issue, assuming contents look correct, you can rebuild on top, it may be worth replacing the cables first, to rule that out.

https://docs.unraid.net/unraid-os/manual/storage-management#rebuilding-a-drive-onto-itself

When reading the "rebuliding a drive onto itself", i miss the "All existing data on this device will be OVERWRITTEN when array is Started".

Cause i never had any situation like this, i need to be absolutely sure how to perform this correctly.
I'm about to:

1. stop the array and reassign DISK6

2. tick "MAINTENANCE MODE"

3. click START

What will happen next? Should the drive be formatted? Will the process of recreating DISK6 start by itself?
Please don't mind me asking, i just need to be sure.

Thank you soo much for your help!

Edited June 26, 20251 yr by Gekko

You don't need to select maintenance mode.

After you reassign the disk and start the array, the rebuild will begin.

The contents of the disk are emulated from the parity calculation by reading all other disks.

https://docs.unraid.net/unraid-os/overview/nas/#parity-protected-array

Rebuild will overwrite the physical disk with the contents of the emulated disk.

This is basically the whole point of parity in Unraid.