Configuration Planning - Lenovo ThinkServer RD240 Software User's Manual

2.7.1.1 Spare Drives
2.7.1.2 Rebuilding
2.8

Configuration Planning

You can use spare drives to replace failed or defective drives in a drive
group. A replacement drive must be at least as large as the drive it
replaces. Spare drives include hot swaps, hot spares, and cold swaps.
A hot swap is the manual substitution of a replacement unit in a disk
subsystem for a defective one, where the substitution can be performed
while the subsystem is running (performing its normal functions).
The backplane and enclosure must support hot swap in order for the
functionality to work.
Hot spare drives are drives that power up along with the RAID drives and
operate in a standby state. If a drive used in a RAID virtual drive fails, a
hot spare automatically takes its place and the data on the failed drive is
rebuilt on the hot spare. Hot spares can be used for RAID levels 1, 5, 6,
10, 50, and 60.
Note: If a rebuild to a hot spare fails for any reason, the hot spare
drive will be marked as "failed." If the source drive fails,
both the source drive and the hot spare drive will be
marked as "failed."
A cold swap requires that you power down the system before replacing
a defective drive in a disk subsystem.
If a drive fails in a drive group that is configured as a RAID 1, 5, 6, 10,
50, or 60 virtual drive, you can recover the lost data by rebuilding the
drive. If you have configured hot spares, the RAID controller
automatically tries to use them to rebuild failed drives. Manual rebuild is
necessary if no hot spares with enough capacity to rebuild the failed
drives are available.You must insert a drive with enough storage into the
subsystem before rebuilding the failed drive.
Factors to consider when planning a configuration are the number of
drives the RAID controller can support, the purpose of the drive group,
and the availability of spare drives.
Configuration Planning 2-33