Hello,

 

I upgraded a 1,5TB disk to a 4TB disk. During the rebuilt of the array another disk crashed. I tried to put the old 1,5TB disk back (which was fine). unRaid now reports "The replacement disk must be as big or bigger than the original." Is there a way to trust the old parity and use the new 4TB for the failing 2TB drive?

 

Bye.

attach diagnostics to your NEXT post in this thread

2 minutes ago, shire said:

another disk crashed

Is that disk still attached? How do you know there is anything wrong with it?

Dec 18 00:31:36 Tower kernel: md: disk12 read error, sector=1953531120

 

I had over 1000 errors during the rebuilt in the logfile.

1 minute ago, trurl said:

Is that disk still attached? How do you know there is anything wrong with it?

 I but the old 1,5TB drive back. Drive 12 is still inside.

5 minutes ago, trurl said:

attach diagnostics to your NEXT post in this thread

 

7 minutes ago, trurl said:

attach diagnostics to your NEXT post in this thread

click the link

3 minutes ago, trurl said:

click the link

 

Edited November 27, 2025Nov 27 by shire

Disk12 is not perfect, but maybe good enough to try to complete the rebuild of the new disk. And you have the original if rebuild has problems.

29 minutes ago, shire said:

Is there a way to trust the old parity and use the new 4TB for the failing 2TB drive?

If you are sure nothing has been written to your server since you replaced that other disk there is something we could try.

1 minute ago, trurl said:

If you are sure nothing has been written to your server since you replaced that other disk there is something we could try.

Yes. Nothing.

Old drive is back (drive1).

1. Tools - New Config, retain all, apply
2. Assign disks as needed, check BOTH Maintenance Mode and Parity Valid boxes then start the array. This will make all disks accepted just as they are with none disabled.
3. Stop array, unassign the disk to be rebuilt, start the array with that disk unassigned. This will disable that disk so it can be rebuilt. At this point, check that the emulated disk is mounted. The emulated contents are exactly what will be rebuilt. If you are unsure post new diagnostics.
4. Stop the array, assign replacement disk, start the array to begin rebuild.

 

Ask if you have questions or doubts.

 

The rebulit is running:

===

UNMOUNTABLE DISK PRESENT:
DISK 12 • WDC_WD40EFZX-68AWUN0_WD-WX42D91ND945 (SDG)
Format will create a file system in all Unmountable disks.
 Yes, I want to do this

PARITY-SYNC/DATA-REBUILD IN PROGRESS. Pause will pause the Parity-Sync/Data-Rebuild.
Cancel will stop Parity-Sync/Data-Rebuild.
WARNING: canceling may leave the array unprotected!

===

 

Disk 12 is mentioned as unmountable. Will this be gone, when the rebuilt is done?

 

 

Disk 12 is shown as emulated. 

1 hour ago, shire said:

Disk 12 is mentioned as unmountable. Will this be gone, when the rebuilt is done?

No, it has to be repaired. And whatever you do, DON'T FORMAT.

 

1 hour ago, shire said:

Disk 12 is shown as emulated. 

Of course it is emulated, the question is whether or not the emulated disk is unmountable.

 

Can I assume you have not proceeded to step 4?

 

Post new diagnostics.

1 hour ago, shire said:

The rebulit is running:

===

UNMOUNTABLE DISK PRESENT:
DISK 12 • WDC_WD40EFZX-68AWUN0_WD-WX42D91ND945 (SDG)
Format will create a file system in all Unmountable disks.
 Yes, I want to do this

PARITY-SYNC/DATA-REBUILD IN PROGRESS. Pause will pause the Parity-Sync/Data-Rebuild.
Cancel will stop Parity-Sync/Data-Rebuild.
WARNING: canceling may leave the array unprotected!

===

 

Disk 12 is mentioned as unmountable. Will this be gone, when the rebuilt is done?

This sounds like you have made a serious mistake. Format is NEVER part of rebuild.

2 hours ago, shire said:

Disk 12 is mentioned as unmountable

from step 3

2 hours ago, trurl said:

At this point, check that the emulated disk is mounted. The emulated contents are exactly what will be rebuilt. If you are unsure post new diagnostics.

 

28 minutes ago, trurl said:

This sounds like you have made a serious mistake.

But maybe not hopeless since it may be possible to read at least some of the original disk.

 

If you are rebuilding after formatting, you are just going to get a formatted disk from the rebuild.

4 hours ago, trurl said:

But maybe not hopeless since it may be possible to read at least some of the original disk.

 

If you are rebuilding after formatting, you are just going to get a formatted disk from the rebuild.

 I haven't used the format button.

 

Edited December 18, 20214 yr by shire

5 hours ago, shire said:

I haven't used the format button.

But you did start the rebuild? So you are rebuilding an unmountable disk. Usually we try to repair the emulated filesystem before rebuilding, but we will have to try repair after rebuild completes. Not really a big deal in this case since you are not rebuilding onto the original disk. So if there are problems with repair we can try to recover files from the original.

2 hours ago, trurl said:

But you did start the rebuild? So you are rebuilding an unmountable disk. Usually we try to repair the emulated filesystem before rebuilding, but we will have to try repair after rebuild completes. Not really a big deal in this case since you are not rebuilding onto the original disk. So if there are problems with repair we can try to recover files from the original.

I startet the rebuilt, which is now done.

 

The array now shows this.

 

What should we do now?:-)

 

 

Edited November 27, 2025Nov 27 by shire

Carry out this procedure against the rebuilt disk and report back on how it goes.

If I understand it correctly I should run:

 

xfs_repair /dev/md12

 

in maintenance mode.

 

The disk shows "auto" at the moment. Would that work? 

3 hours ago, shire said:

xfs_repair /dev/md12

 

in maintenance mode.

Correct