American Megatrends MegaRAID Express 500 - Manual (Page 28)

MegaRAID Express 500 Hardware Guide 14
Disk Rebuild
You rebuild a disk drive by recreating the data that had been stored on the drive
before the drive failed.
Rebuilding can be done only in arrays with data redundancy such as RAID level
1, 3, 5, 10, 30, and 50.
Standby (warm spare) rebuild is employed in a mirrored (RAID 1) system. If a
disk drive fails, an identical drive is immediately available. The primary data
source disk drive is the original disk drive.
A hot spare can be used to rebuild disk drives in RAID 1, 3, 5, 10, 30, or 50
systems. If a hot spare is not available, the failed disk drive must be replaced
with a new disk drive so that the data on the failed drive can be rebuilt.
The MegaRAID Express 500 controller automatically and transparently rebuilds
failed drives with user-definable rebuild rates. If a hot spare is available, the
rebuild starts automatically when a drive fails. MegaRAID Express 500
automatically restarts the system and the rebuild if the system goes down during
a rebuild.
Rebuild Rate The rebuild rate is the fraction of the compute cycles dedicated to rebuilding
failed drives. A rebuild rate of 100 percent means the system is totally dedicated
to rebuilding the failed drive.
The MegaRAID Express 500 rebuild rate can be configured between 0% and
100%. At 0%, the rebuild is only done if the system is not doing anything else.
At 100%, the rebuild has a higher priority than any other system activity.
Physical Array A RAID array is a collection of physical disk drives governed by the RAID
management software. A RAID array appears to the host computer as one or
more logical drives.