Hi everyone,

I need some advice on the most efficient way to upgrade my array. Here's my current setup:

Current configuration:

• Parity 1: 24TB

• Parity 2: 18TB

• Data drives: Various sizes (all under 18TB)

• Just purchased: Two new 24TB drives (currently pre-clearing both!)

Goal: Add both 24TB drives to my array, which requires upgrading the 18TB parity first.

My question: What's the fastest sequence of operations to get back to normal dual parity protection?

Since I'm pre-clearing both drives, I'm considering:

Option A (seems fastest):

1. Stop array

2. Unassign 18TB from Parity 2 slot

3. Start array (drops to single parity)

4. Add first pre-cleared 24TB as data drive (instant - no clearing needed!)

5. Add second 24TB as Parity 2 (parity build ~24-30 hours) Total: ~24-30 hours with new capacity available immediately

Option B:

1. Replace 18TB parity with one 24TB (parity rebuild ~24-30 hours)

2. Add second pre-cleared 24TB as data drive (instant) Total: ~24-30 hours but dual parity maintained throughout

My main concern: If I remove the 18TB parity drive (Option A), will Unraid accept that my remaining 24TB parity is still valid, or will it force a rebuild? I've read that Parity 1 uses XOR and Parity 2 uses Reed-Solomon, so they're independent? I want to confirm before I proceed.

Option A seems like the clear winner since I get the new capacity online immediately and the total time is the same. Just want to make sure I won't trigger an unnecessary parity rebuild when I remove Parity 2.

Can anyone confirm this approach will work as expected?

Thanks in advance!

Edited July 10, 20251 yr by tim000x3

Let me point out one thing. Adding files to the array while updating/building parity will slow down both operations an probably require more time for complete the combined operation than rebuilding parity first and then adding the new disk. (Which if it is precleared, takes about two minutes!)

By the way, while you are rebuilding Parity 2, you only have the illusion of dual parity. You can only have one other disk fail and not loss data. (If you think about it, when you remove PArity2, that becomes a disk "failure"!)

You will have only single parity the instant you remove Parity 2 . No rebuild of parity is required for this operation.