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1.4.4 High availability
1.4.4.1 Creating Hot Spares
A hot spare drive is an unused online available drive, which is ready for re-
placing the failure disk drive. In a RAID level 1, 0+1, 3, 5, 6, 30, 50 or 60 raid
set, any unused online available drive installed but not belonging to a raid set
can define as a hot spare drive. Hot spares permit you to replace failed drives
without powering down the system. When RAID subsystem detects a hard
drive failure, the system will automatic and transparent rebuilds using hot
spare drives. The raid set will be reconfigured and rebuilt in the background,
while the RAID subsystem continues to handle system request. During the au-
tomatic rebuild process, system activity will continue as normal, however, the
system performance and fault tolerance will be affected.
Important:
!
The hot spare must have at least the same or more capacity as the
drive it replaces.
1.4.4.2 Hot-Swap Disk Drive Support
The RAID subsystem has built the protection circuit to support the replace-
ment of UDMA hard disk drives without having to shut down or reboot the
system. The removable hard drive tray can deliver "hot swappable," fault-
tolerant RAID solutions at prices much less than the cost of conventional
SCSI hard disk RAID subsystems. We provide this feature for subsystems to
provide the advanced fault tolerant RAID protection and "online" drive
replacement.
1.4.4.3 Hot-Swap Disk Rebuild
A Hot-Swap function can be used to rebuild disk drives in arrays with data
redundancy such as RAID level 1, 0+1, 3, 5, 30, 50 and 60. 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. If a hot spare is available, the
rebuild starts automatically when a drive fails. The RAID subsystem auto-
Introduction
1-17
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