Currently I have two 8TB parity drives, if I wanted to say, drop down to one 10TB parity drive, how would I accomplish this?

 

My thinking is this:

 

Drop down from two 8TB parity drives to one. Would this mean a recalculation of parity? 

Remove parity drive, add 10TB as new parity, let parity recalculate.

 

Sound about right?

You are wanting to only have one 10TB parity drive and no 8TB drives, right? If so, you should just be able to create a new config and just not put either 8TB drives in the parity slots and only put the 10TB. When you start up the new config it will just completely write the parity drive from scratch. 

Right except I am at the max physical drive limit, so I would have to physically swap out one 8TB drive.

 

I think what I would do is this.

 

Stop the array.

Remove both parity drives.

Start the array.

Stop the array.

Swap out one 8TB drive for new 10TB drive, assign it to parity.

Start the array which would start the parity calculation.

You might want to start by only replacing one parity drive (ideally parity 1) so that you remain protected, and only remove the second one when the parity 1 drive has been rebuilt.  Removing both at once and then rebuilding parity means you lose data if one of the data drives fails before the parity rebuild has completed.

I think it would be a bit more like this:

 

Stop the array

Remove one parity drive and put the 10TB drive in

Create new config putting the remaining 8TB drive in a normal array slot (not sure if you have to preclear/wipe/do something to it first) and put the 10TB drive in the sole parity slot

Start array and build parity. 

 

I could be slightly wrong with that but you do have to create a new config. 

OK, I am not too concerned about leaving the array unprotected as this is a backup server, so it's duplicate data.

3 hours ago, itimpi said:

You might want to start by only replacing one parity drive (ideally parity 1) so that you remain protected, and only remove the second one when the parity 1 drive has been rebuilt.  Removing both at once and then rebuilding parity means you lose data if one of the data drives fails before the parity rebuild has completed.

 

This!

 

There is no downside.

This is a situation in which the dual parity is actually the one and only parity protection you will have. It's like you've had a backup safety net the whole time, and now you're replacing your primary net and decide you don't need the secondary net anymore while it is being replaced. As good as you are walking the tightrope, don't remove both safety nets! You've invested in dual parity for that extra slight tweak in protection, and now you're ready to do a full disk operation when risk is highest. The second parity is of more value now than it has been in its whole life! It's its moment to shine!   

 

Nooooo ... Mr. Bill ...