Does a replacement RAID disk need to be empty?
Lazy question here. I'm about to replace both RAID 1 SATA disks from a live server, ensuring each disk has fully built before replacing the other. This is a SuperMicro server which I would assume holds a RAID controller
The replacement disks I'm using have data on them already which I couldn't have any care about losing. Is it required for those disks to be BLANK in order for the swap to remain successful?
Having to save wiping the disks beforehand would save a lot of time Thanks
Solution 1:
No. The RAID array doesn't care.
During setup of the array the controller will trigger a process to copy the contents of the first disk to the second but it won't care what is on either disk to begin with.
This may seem like a waste of time to you, but the controller has no idea what is real data on the disk and what is not. The goal of RAID 1 is to achieve two identical disks.
You should simply treat the disk as you would any other and let the process continue while carrying on installing and setting up as you normally would. Delete partitions if they are still showing (from the first disk), install your operating system and so on. Active reads and writes from the host system should take priority over the RAID rebuild, but your disk performance may not be at 100% until the rebuild is complete.
Or, if you are simply trying to clone the disk that already has a working install, just carry on using the system.
Solution 2:
They don't need the be blank. They will be re-formatted by the RAID controller anyway. Just make sure the new disks are bigger than the old disks.
Have a care though (this is a general concern with RAID setups, especially RAID1 and RAID5).
During the re-build of the first new disk the other (old) disk will receive a very heavy read load, because it will have to be read once in its entirety in other to do the rebuild. If that is an old disk already close to end-of-life that extra stress may push it over the edge.
With RAID5 it is even worse: For EACH new disk ALL the remaining old disks need to be read at least once.
The chances of having any of the old disks fail are significant.
Just make sure you have a full backup before doing this, because any failure of one of the old disks while re-building will be fatal for your data.