First of all I'd recommend you replace the hard drive, because if it went offline once, it will quite possibly fail again, maybe just due to a few bad blocks on it, and if that happens during a rebuild, it causes data loss.
Anyway if you want to take the risk, RWC2 wouldn't allow you mark it as a hot spare because there is still RAID configuration information on the disk, and that's now identified as foreign RAID configuration. I don't have a RAID card right beside me, so I can't tell you the exact steps, but the idea would be clearing the foreigh configuration first, and then make it hot spare.
OK thank you very much for the answer.bought a new disk today and inserted it as a hotspare and everything worked out perfectly.
Although i have another question.
when i select one or any of the disk in the left panel in RWC2 i get an error msg in the log panel on the bottom.
I have tried to find information about this but cant seem to find any that really tells me what it really means.
LOCALIZED MESSAGE = Controller ID: 0 Unexpected sense: PD = --:--:4 - Invalid field in CDB, CDB = 0x4d 0x00 0x4d 0x00 0x00 0x00 0x00 0x00 0x20 0x00 , Sense = 0x70 0x00 0x05 0x00 0x00 0x00 0x00 0x0a 0x00 0x00 0x00 0x00 0x24 0x00 0x00 0x00 0x00 0x00
I get this error msg when i click on any of my disks in the array? And i think i actually have always gotten it, but havent really agnoliged it untill now.