Hello all!

I have a scenario I'd like to run by everyone. I have:

1 x 20TB disk (parity)

4 x 12TB disks (data)

5 x 4TB disks (data)

I've been slowly upgrading my 4TB disks as I've had those for years and decided to make an Unraid configuration. My PC case has 10 available 3.5 inch drive slots. All are currently occupied.

I bought a 26TB drive. I want to replace the 20TB parity drive, and move the 20TB parity drive to replace one of the 4TB drives.

Am I able to install the 20TB drive with the 26TB and remove the 4TB simultaneously, or do I need to:

Replace the 4TB with the 26TB > let that rebuild > move the 26TB drive to the parity slot, move the 20TB to the 26TB slot.

Thank you for any info/help!!! :-)

Edited November 12, 2025Nov 12 by omegajvn
To clarify

If you have single parity, you will need to first upgrade parity, and only then can you replace the other disk.

Thanks Jorge!

Hypothetically, if I had an extra physical slot, could I install the 26TB, make it my second parity, and move the 20TB (first/original parity) to a data drive? Would this keep parity the entire time, or is it even possible?

Also, I've read that Unraid does not care what physical slot/port that a drive is connected to. It only cares about the serial number of the drive for identification. If I wanted to relocate the physical location of the parity drive, could I do that here at the same time? For instance, the 20TB parity drive is at the top of my stack and I want to move it to the bottom. Currently, the 4TB is at the bottom. Basically want to do a flip. Could I move that 4TB to the spot where the 20TB is now, and put the 26TB where the 4TB slot?

I'd then just need to select the 26TB to be put in the Parity slot, like I would have to do otherwise if I simply replaced the 20TB in that top slot?

(I apologize if that sounded confusing)

Edited November 12, 2025Nov 12 by omegajvn

Unless I am missing something, this sounds like a 'Parity Swap' would work. See here for those instructions:

https://docs.unraid.net/unraid-os/using-unraid-to/manage-storage/array/replacing-disks-in-array/#parity-swap

I believe that is for when you have an extra slot/port available to simply add an extra drive into the array for doing all the moves. I don't. I'm trying to replace my old parity (20TB) with a new drive (26TB) and move the 20TB to replace an old 4TB.

I guess I have no problem simply replacing the 20TB with the 26TB, let it build, then replace the 4TB with the 20TB in two moves instead of trying to do this in a single move.

Unless I'm missing something.

11 hours ago, omegajvn said:

Hypothetically, if I had an extra physical slot, could I install the 26TB, make it my second parity, and move the 20TB (first/original parity) to a data drive?

Yes, but still only the new parity was synced. The main advantage is that the array would remain protected during the sync.