My disk 11 does not have anything copied to it, and never has anything copied to it. I'd like to take it out of my array and make it a cache drive. What's the best way to do this?

 

I was planning on just stopping the array, unassigning the drive from disk 11, and then making it the cache drive, starting the array and then do a parity sync. is this a good plan?

You are close.

 

You must stop the array, un-assign the disk11, and re-assign it as the cache drive.

Then, you must set a new disk configuration.

(If on 5.x, Utils->new Config)

That will immediately invalidate parity, and parity will again be initially calculated when you next start the array.