Hello.

I have a problem with my unraid server.

My initial configuration is :

Parity : 4to

Disk 1 : 4to

Disk 2 : 3to

Disk 3 : 2to

Cache 1 : 1to

Cache 2 : 1to

Basic plan limited to 6 drives

I wanted to replace the Disk 3 (2to) with a brand new 4to HDD. But the drive was faulty from the factory. I respected the procedure to change the drive. But while rebuilding the new drive an error occured quite rapidly. The drive is simply dead (mechanical noises, Unraid or my computer can see it but can't do anything else)

I wanted to put back the original drive in the array but I can't because Unraid is now expecting a 4to drive, not a 2to one.

I will send the drive back and get a replacement one but it will take to much time as i don't have access to my data and i need it as quickly as possible.

I know there is a method to shrink the array and start a new configuration with one less drive and then expend the array with the new drive. But it requires to move the files from the third drive to the other ones before. And that is impossible for me right now as I cant' add the 2to drive to the array.

I have enough space on the other two drive.

So is there a way to recover the files from the parity to move them to the other two drives without losing any data so I can shrink the array ?

Any other helpfull solution ?

Thanks for your help !!

Edited November 16, 2025Nov 16 by Kaneda241

Assuming the old disk was good, you can do a new config with it (Tools - New Config - Keep all - Apply), then assign the old drive, check parity is already valid before array start, then run a correcting parity check; a few sync errors are expected.

Yes. The old disk was good.

I will try that. It makes sense.

Thank you.

The parity is rebuilding from the other drives. It seems to work. See you in a few hours if everything is OK.

17 hours ago, JorgeB said:

Assuming the old disk was good, you can do a new config with it (Tools - New Config - Keep all - Apply), then assign the old drive, check parity is already valid before array start, then run a correcting parity check; a few sync errors are expected.

Partition rebuilding is finished. Not a single error. No data loss.
Thank you so much!!!