I have two drives in a RAID 1 (mirroring) array. Hardware RAID using whatever is built into an Intel motherboard (Asus P5BE).
I'd like to remove one drive but keep the data in both (I want to put one of the drives into another machine).
Can I go into the RAID configuration and remove the array and have the data remain?
Yes, telling it to remove the RAID array straight up has a 99% chance that you will end up with identical non-RAID drives with the original data on them, so you can just do that if you want to. Of course, it may be a complete jerk for you and wipe the drives for no good reason, but this is very unlikely.
What you can do if you're not sure and absolutely can't risk losing the data at all is just take out one of the drives and boot the system. When it yells at you, just say that you want to remove the RAID. Then you can take that disk out and do the same with the other disk. This way, there is no chance that it can erase both drives and very little chance that you lose the data on either of them.
This sort of depends on the installed OS. I'd quiesce the system; break the mirror by flagging one of the drives as unusable; remove.
Place it into the second server and see what happens. If it becomes fully operational, then dependent upon the OS, you may have to alter/reconfigure system related parameters, e.g., IP, hostname, etc. to prevent duplication of entities on the same network.
Once this is fully operational, restart the source/primary/original server.
@marcusw is right on but I would backup all my data before attempting this. This would reduce your risk to none.
I would also say that some advertised raid support on motherboards are not all hardware based some software based and work with the operating system. Additionally if it is low level software based raid destroying the raid may not work as easily as one may expect
