If one of the hard disk drives in your RAID array fails and you don't have a hot spare (hot standby) hard disk drive, you may be able to perform a hot swap, where you remove one hard drive and replace it with the exact same drive, without powering down your system. Ideally, users of the RAID array won't even know anything happened.
In order to perform a true “hot swap,” the RAID drives must have special connectors to maintain the connections between the drive and the bus. Most SCSI SCA buses have this special design. Additionally, the enclosure that houses your RAID array drives and RAID controller must have open drive bays so you can access the drives through the front of the case for replacement without unplugging the system.
The Next Best Thing: A Warm Swap
On RAID servers that use IDE/ATA drives, the best you can do in the event of hard drive failure is a warm swap, where the power remains on and the operating system functions, but activity must stop on the bus during the swap. This means there will be a time when the server is “down” and cannot be used.
Do You Have a Standby Hard Disk Drive?
Of course, you can't perform a hot, or even a warm, swap on your RAID array if you don't have a spare disk drive. The longer you wait to replace a failed drive, the greater the chances you'll experience RAID array failure resulting in the loss of data.
Your RAID server -- and the data you store on it -- is crucial to your business. Why take chances? Keep a spare drive on hand.
But remember, you can always call 24 Hour Data to help with RAID data recovery. We understand.