Downgrade from dual parity to single

[Bobat]

Here is my current config:

2 parity drives (3tb each)

1 cache drive (1tb ssd)

12 data drives (mix of sizes from 1 - 3tb)

 

I just bought 2 8tb drives on a black friday deal.  The goal is to both increase the capacity of the array and consolidate and eliminate one of the smaller drives.  I think the dual parity was overkill, so the final config will be a single 8tb parity drive and the other 8tb drive will be put into the array as a data drive.  I think the steps for this would be:

1. Stop the array
2. Unassign both of the parity disks
3. Assign one of the 8tb drives as parity, leave the old parity disks unassigned
4. Start the array
5. Wait for parity to rebuild
6. Power down, pull one of the old 1tb data disks and replace with the other 8tb disk (precleared previously)
7. Assign the new 8tb drive into the old slot, let it rebuild from parity
8. Preclear the old parity disks, add them to the array as data disks

 

Sound right or am I missing something?

[ashman70]

I asked the same question recently and the general consensus was to only unassign  one parity drive, replace it with the 8TB drive, let parity rebuild, once rebuilt, unassign the the other parity drive, let parity rebuild.

 

Your method leave the array unprotected with no parity drives, so should a disk fail while parity is rebuilding in your scenario you lose data, by having the other parity drive, you are protected. You can have two different sized parity drives.

[Bobat]

Thanks.  I think I initially misunderstood how dual parity was working and thought that both parity drives had to be available to have protection in a dual-parity setup.  After reading this I get why having either of the parity drives available gives me one-drive failure tolerance while the other parity is rebuilding.

 

So is Parity 1 always the XOR and Parity 2 is the Reed-Solomon?  So I want to replace Parity 1 with the new larger drive, let it rebuild, and then unassign Parity 2?