Question about shrinking array

[jebusfreek666]

I have read the wiki, and will be removing a disk from my array in the near future. My plan is to leave one hot swap slot free. I would like to remove disk 6 of a total of 9 disks. The reason I want to remove this specific disk is that after upgrading most of my drives from 6TB to 12TB, I am left with an odd order in which some disks are 6's and some are 12's. What I mean is disk 1-5 are all 12TB, disk 6 is 6TB, disk 7 is 12TB, and disk 8&9 are 6TB. If I remove disk 6 (which is in a hot swap bay) I would be left with the larger capacity on top, and the smaller capacity (which I also plan on changing as soon as the 12's go back on sale) on the bottom. My question is, if I follow the "remove then rebuild parity" method, will unraid renumber my disks, or will it leave a hole? Will it show disks 1-6 as 12TB, and 7&8 as 6TB. Or will it leave a hole where disk 6 was and show 1-5 as 12TB, disk 6 as an empty spot, 7 as 12Tb, and 8&9 as 6TB. And if it will leave a hole in the disk 6 slot, while I am assigning disks again can I just change the number of disk 7-9 to be disk 6-8 before rebuilding parity or will that cause problems?

Edited January 9, 2020 by jebusfreek666

[FreeMan]

Unraid will leave a hole in the numbering sequence. It won't care and it doesn't matter except to the neat and orderly among us.

 

If you're running a single parity, the disk order won't matter, so you can move disks up. If you want to leave the 6TB in the array but have the 12s together and have the 6s together, you can swap disks 6 and 7.

 

All bets are off if you're running dual parity - I'm not and I have no idea how that works.

[jebusfreek666]

I am running dual parity...

[JorgeB]

Parity2 will be invalid if disk order is changed and will need re-sync, like mentioned parity1 stays valid.

[jebusfreek666]

4 minutes ago, johnnie.black said:

Parity2 will be invalid if disk order is changed and will need re-sync, like mentioned parity1 stays valid.

So, just to make sure I do this correctly, after I move all the data off the disk I go to new config and click retain current configuration. After that I move disk 7-9 to be disk 6-8, and just leave the disk that was 6 unassigned? Then apply and do not click the "parity is already valid" option. After that, just restart the array and let it rebuild parity?

[JorgeB]

6 hours ago, jebusfreek666 said:

Then apply and do not click the "parity is already valid" option

Parity1 will only be valid if the disk you're removing is cleared first, options for shrinking array are explained here:

https://wiki.unraid.net/Shrink_array

[jebusfreek666]

3 hours ago, johnnie.black said:

Parity1 will only be valid if the disk you're removing is cleared first, options for shrinking array are explained here:

https://wiki.unraid.net/Shrink_array

Right, I get that and will be clearing it first and moving the data to other disks on the array. But since parity will be valid for parity 1, but not for parity 2 should I not click the "parity is already valid" option and just rebuild after? Or do I click that it is valid (half the parity disks are?) and then still rebuild because parity 2 wont be.

Edited January 10, 2020 by jebusfreek666

[itimpi]

32 minutes ago, jebusfreek666 said:

Right, I get that and will be clearing it first and moving the data to other disks on the array. But since parity will be valid for parity 1, but not for parity 2 should I not click the "parity is already valid" option and just rebuild after? Or do I click that it is valid (half the parity disks are?) and then still rebuild because parity 2 wont be.

One option might be to start the array without parity2 assigned and tick the parity is valid box.    That way you get a protected array as early as possible (assuming parity1 IS valid).     You can then stop the array; assign parity2; start the array to build the contents of parity2.    You will still want to carry out a parity check afterwards to make sure parity1 WAS valid.

 

The alternative is to make no assumptions about parity and not tick the parity is valid box so that both parity1 and parity2 get rebuilt in parallel when you start the array.

[jebusfreek666]

Cool, thanks @itimpi. As always, super helpful!