I want to compare the performance of the controllers. Is it safe for me to put the controller in, assign the disk correctly then do a parity check (no writing to the array)?

 

So if a controller is faulty, is my array safe?

 

 

That should be fairly safe. Nothing is guaranteed but it should be OK if you don't write.

 

Peter

 

That should be fine.  Another option is to preclear some new disks (not your data disks!) on the new controller.