Shrink array and swap parity drives

[Fleat]

I would like to shrink my Unraid array by removing 4 data drives and both of the parity drives. I intend to spin up another NAS solution for testing purposes and as a backup for the Unraid solution. I have attached a diagram of what I intend to do. 

Ideal End Result: Unassigned Disk 1 (Toshiba 5TB) to Parity 1, all WD Red 8TB drives removed from the array & parity

 

I started here: https://wiki.lime-technology.com/Shrink_array

 

Can I do this swap while remaining fault tolerant as one of the existing parity drives will still have the calculated parity without using the clear-me script on each drive? Here are a couple of the approaches I am considering, and I am wondering if these are feasible

 

Interim config with 1 valid parity drive and a new dual parity - Will I remain fault tolerant?

1. New config
2. Remove Parity Disk 2 
3. Remove Array Disks 7, 8, 9, and 10 from the config (Disks are empty)
4. Check the box "Parity is already valid"
5. Array Result: Array with 1 8TB parity drive and 6 5TB Data Drives - Is the parity truly still valid here?
6. Stop array and add Unassigned Disk 1 (Toshiba 5TB) as a Dual Parity and build the parity
7. New config
8. Remove WD 8TB and leave Unassigned Disk 1 (Toshiba 5TB) as the only parity
9. Check the box "Parity is already valid"
10. Start the array

 

Abandon parity and follow this: "Do not click the check box for Parity is already valid; make sure it is NOT checked; parity is not valid now and won't be until the parity build completes"

1. New config
2. Remove Parity Disk 1, 2
3. Remove Array Disks 7,8,9, and 10 from the config (Disks are empty)
4. Add Unassigned Disk 1 (Toshiba 5TB) as Parity Disk 1
5. Make sure "Parity is already valid" is unchecked
6. Start array and let the parity rebuild

 

 

 

[JorgeB]

1 hour ago, Fleat said:

Array Result: Array with 1 8TB parity drive and 6 5TB Data Drives - Is the parity truly still valid here?

no

 

1 hour ago, Fleat said:

Can I do this swap while remaining fault tolerant as one of the existing parity drives will still have the calculated parity without using the clear-me script on each drive?

You can't remove disks (even if they're empty) without clearing them and maintain parity.

[Fleat]

2 hours ago, johnnie.black said:

no

 

You can't remove disks (even if they're empty) without clearing them and maintain parity.

 

Great, thank you for the information. Leaning towards option 2 because it would be much quicker. Do you foresee any problems with that (if I don't lose an array drive during the parity rebuild)?

Edited November 21, 2017 by Fleat

[JorgeB]

Use option 2, if all disks are working well there shouldn't be any issues, but if you can leave the disks you're removing and the array data intact during the re-sync and if anything goes wrong you can go back to the old assignments and rebuild any failed disk (or two since you have dual parity).

[Fleat]

2 minutes ago, johnnie.black said:

Use option 2, if all disks are working well there shouldn't be any issues, but if you can leave the disks you're removing and the array data intact during the re-sync and if anything goes wrong you can go back to the old assignments and rebuild any failed disk (or two since you have dual parity).

 

Will do - thank you for the advice!