Hi.

I have an array of 5 HHDs, 4 data + 1 parity, current parity is 16 TB.
I'm trying to carry out a parity swap as described here: https://docs.unraid.net/unraid-os/using-unraid-to/manage-storage/array-configuration/#parity-swap

TLDR - I pre-cleared a new larger drive I want to add:

####################################################################################################
#                              Unraid Server Preclear of disk ZR578FYC                             #
#                            Cycle 1 of 1, partition start on sector 64.                           #
#                                                                                                  #
#   Step 1 of 5 - Pre-read verification:                  [24:11:38 @ 206 MB/s] SUCCESS            #
#   Step 2 of 5 - Zeroing the disk:                       [24:14:23 @ 206 MB/s] SUCCESS            #
#   Step 3 of 5 - Writing Unraid's Preclear signature:                          SUCCESS            #
#   Step 4 of 5 - Verifying Unraid's Preclear signature:                        SUCCESS            #
#   Step 5 of 5 - Post-Read verification:                 [24:11:48 @ 206 MB/s] SUCCESS            #
#                                                                                                  #
####################################################################################################
#       Cycle elapsed time: 72:38:15 | Total elapsed time: 72:38:16                                #
####################################################################################################

And am trying to do the following:

• Unassign old 16TB parity drive from parity slot

• Assign new pre-cleared 18TB drive to parity slot

• Assign old 16TB parity drive to a data slot

Expected behavior:

• Somewhere in the Array Operation area, around the Start button, a Copy button / checkbox appears, allowing my to carry over the parity information to the new drive without running a 80 hours parity sync with array unprotected.

Am I missing a step?

Old configuration:

New configuration:

Array Operation area after swapping the disks:

Edited October 22, 2025Oct 22 by semioniy

Parity swap only works with a disabled disk, disk 5 is not disabled according to the 1st screenshot; it doesn't exist.

Does this mean that in my case (no disk has failed) I can't replace the parity drive with a larger one without running a considerable amount of time with array unprotected, while the parity is recalculated?

Parity swap is not to keep the array protected; it is to replace a data disk when the new one is larger than parity.

Upgrading parity is done directly. If you want the array to remain protected, you have a couple of options.

• Do it in maintenance mode; if it fails, you can reinstall the old parity.

• Add the new one as parity2, then remove parity once it's done.

Ok, thanx. So to summarize:

• There's no copying mechanism that'll transfer parity data from old parity drive to the new one. A new parity will have to be calculated from the ground up.

And my options are (given that I don't want to run unprotected for the length of parity calculation on the new drive):

• Do it in maintenance mode; if it fails, you can reinstall the old parity.

Taking array offline for a considerable amount of time (in my case probably 2-3 days).

• Add the new one as parity2, then remove parity once it's done.

Getting stuck with a disk labeled Parity 2 with no way to change this label later on (that will bother me immeasurably).

I'm starting to consider running unprotected with the array live while calculating a new parity 😅🫡

17 minutes ago, semioniy said:

Taking array offline for a considerable amount of time (in my case probably 2-3 days).

FYI, the parity copy portion of the parity swap is also done with the array offline.