I have a Dell Poweredge 2900 that I'm upgrading from 4x SATA 250GB Drives in a RAID 5 situation to 2x SATA 1TB Drives in a RAID 1 situation. The box is running Windows Server 2003, with a PERC5/i controller card. As far as I can tell without too much prodding, the server is running RAID 5 with three drives. The guy before me added a fourth HD, and swapped a drive out after one failed, but the array itself is still only using three drives and the OS is still partitioned for 500GB total. (50GB C:, 450GB D:) We're looking to replace the current OS with Server 2008 R2, doing a clean install on the new 1TB drives.
I have some experience with creating new arrays from scratch, but this will be my first migration to a new array after one was already in place. I already have backups in place with for normal production reasons (can't have too many!), and plan on making at least two backup images as well.
My question is, when I create the new array (Drop in the new drives, go into the controller and create a new RAID 1 array), what would happen if I dropped the old set of four drives back into the machine? My thought is, if something went wrong during the migration over the weekend, I could drop the original four drives back into the server and have them up and running like nothing happened. Would I have to rebuild the array from scratch, or would the card recognize the array existing, or would it all just catch fire in my face to spite me?
It's an odd question, but I have this paranoia sometimes.