HP StorageWorks 500 Modular Smart Array - Manual (Page 144)

Troubleshooting
HP StorageWorks Modular Smart Array 500 System User Guide D-11
Always perform disk drive replacement as soon as possible. In addition, all logical
volumes on the same array as the drive being replaced should have a current valid
backup.
If another drive in the array fails while you are rebuilding a previously failed drive,
fault tolerance is compromised and all data on the array is lost, with the following
exceptions:
• In a mirrored (RAID 1) configuration, failure of a drive that is not mirrored to
any other failed drives.
• A second drive failure in a RAID ADG configuration.
Take these precautions when removing failed drives to minimize the likelihood of
compromising the logical drive data:
• Do not remove a degraded drive if any other member of the array is offline (the
online LED is off).
• Do not remove a failed second drive from an array until the first failed or missing
drive has been replaced and the rebuild process is complete. (When the rebuild is
complete, the online LED on the front of the drive stops flashing.) Exceptions
include RAID ADG configurations, as any two drives in the array can be
replaced simultaneously
When a hard drive is replaced, the controller uses fault tolerance data on the
remaining drives in the array to rebuild data onto the replacement drive. If more than
one drive is removed at a time, the fault tolerance data is incomplete. The missing
data cannot then be reconstructed and is likely to be permanently lost.
Drive Failure in NetWare
Although hard drive failures are not common, it is important to protect all critical
data. To be sure of a quick and transparent recovery, HP recommends that you
configure the array controller using a hardware-based fault tolerance method. These
methods are more reliable than software-based fault tolerance methods or drive
duplexing.
HP also recommends that you use good backup procedures, in case of catastrophic
failure.