Hopefully my title is self explanatory but ultimately I want to expand the capacity of my system but the drive I am adding is larger than my parity so I need to replace the parity and then I want to add the old parity disk to my array.

The documentation's procedure only seems to reference replacing a failed data disk. I don't want to do that, none of my disks are failed, I just want to replace parity and expand the size of the array. Would I still follow the same procedure? Swap the new disk into parity and assign the old parity disk as a data disk (but not a failed data disk)?

Edited November 17, 2025Nov 17 by jjross

Upgrade parity first, then use old parity to expand the array.

Yes, but how?

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

Thank you, as I said, I read the docs but I also know that sometimes they are out of date.

Also, the section on "parity swap" specifically calls out:

"Before starting, ensure the data drive you want to replace is disabled. If the drive has failed (shows a red indicator), it is already disabled. If the drive is healthy but you want to replace it, unassign the drive and start the array once without it to force Unraid to mark it as disabled."

I do not want to replace a data disk. I want to take the old parity disk and add it to the pool. This doesn't seem to be called out in the instructions. It does, however, say this:

"This procedure is only needed for replacing data drives in an Unraid array with a disk larger than the current parity drive. If you only need to upgrade your parity drive, simply remove the old parity drive, add the new one, and start the array. Parity will rebuild automatically"

So I'm guessing I just need to pull the parity drive and add a new one? Is there a way to copy the existing parity data so I have some redundancy while parity is rebuilding? I do see mention of a "copy" button when I am replacing a failed data disk but nothing when adding a new disk.

You don't need to do a parity swap, just a standard disk replacement.

12 hours ago, jjross said:

So I'm guessing I just need to pull the parity drive and add a new one?

Yes.

12 hours ago, jjross said:

Is there a way to copy the existing parity data so I have some redundancy while parity is rebuilding?

Not directly, but if you do this in maintenance mode and keep the old parity drive intact until the rebuild finishes then in the event of a data drive failing there is a procedure that would allow you to temporarily reinstate the old parity drive to handle recovering the failed data drive.

Another possibility is to add the new parity drive as parity2 and only remove parity1 after successfully building parity2. That leaves you at the end with a parity2 and no parity1 (which is valid) but some people do not like ending up in this position.

Thank you for the help.