Hi All, hope I am in the right place. Happy to say (and fingers crossed) Unraid has been incrediby reliable for me and so this is the first time in years I'm looking for support / community feedback.

I am adding and removing disks from the array for the first time ever, looking to confirm that I am about to do this correctly, or any feedback appreciated.

My server consists of 5 hdds:
Parity - WDC_WD80EMAZ
Disk 1 - WDC_WD80EMAZ

Disk 2 - WDC_WD80EMAZ
Disk 3 - ST4000DM000
Disk 4 - Hitachi_HDS5C3030ALA630

Some of these are shockingly old but still working. It's time to replace them. The Parity and first two disks are 8TB, then 4TB and 3TB respectively = 23TB Total

The state I want to get this server to is 34TB total with 2 parity disks:
Parity 1 - WD Red Plus WD120EFGX - 12 TB
Parity 2 - WD Red Plus WD120EFGX - 12 TB

Disk 1 - WDC_WD80EMAZ - 8 TB
Disk 2 - WDC_WD80EMAZ - 8 TB

Disk 3 - WDC_WD80EMAZ - 8 TB
Disk 4 - WDC_WD101KRYZ - 10 TB

My plan is do it this way:

0) Shutdown. Open the case and add two WD120EFGX disks. Power up.
1) Stop the array, Add first WD120EFGX - 12 TB as Parity 2,Start the array, Let the array rebuild

2) Stop the array, Remove Parity 1, Start the array. Stop the array, Add second WD120EFGX - 12 TB as Parity 1, Start the array, Let the array rebuild

3) Stop the array, Remove Disk 3 (ST4000DM000). Add the previously-a-parity-disk (WDC_WD80EMAZ) to the slot where ST4000DM000 was. Start the array, Let the array rebuild

4) Stop the array. Remove Disk 4 (Hitachi_HDS5C3030 ) because it's old and I want it out of there. Start the array, Let the array rebuild.

4b) ... [Down the road, when WDC_WD101KRYZ has been freed up from another box] Shutdown. Remove ST4000DM000 (old disk 3) and Hitachi_HDS5C3030 (old disk 4) from the case, add WDC_WD101KRYZ into the case. Power up. Stop the Array, assign WDC_WD101KRYZ to disk 4 slot. Start the array, Let the Array rebuild.

Did I miss any steps? Missing or extra starts/stops of the array?

Looking at that, it's a lot of steps, array rebuilds, and 24h+ waits for array to rebuild. Doesn't really matter unless there's a better way to do it?

Edited December 10, 2025Dec 10 by bmcent1

As long as you do it maintenance mode (so no data writes happen) you could change both parity disks in the same step. Just keep the old parity1 intact until parity is rebuilt in case a data drive fails while building parity as that leaves a recovery option available.

Your current step 4 involves rebuilding parity again as you are removing a drive so maybe omit step 4 at this point and leave current disk4 in place until you are ready to replace it?

Thank you!