Using Spare Drives - Compaq N2400 - TaskSmart - 1 GB RAM Administration Manual

6-32 Compaq TaskSmart N2400 Administration Guide

Using Spare Drives

To greatly increase the fault tolerance of your TaskSmart N2400 appliance,
Compaq recommends that you use at least one of the drives in the storage
enclosures as an online spare drive. Using the recommended configuration of
RAID 5 (distributed data guarding) on the external enclosure drives, in
combination with an online or hot spare, achieves the highest level of
protection. In case of a drive failure, an online spare is assigned to an array. If
the spare is available, it acts as an immediate replacement for the failed drive.
Recovery operations start automatically to rebuild the information from the
failed drive onto the spare drive, using the remaining drives and the distributed
data guarding (parity) information.
NOTE: Until the rebuild process is complete, a spare drive cannot prevent the failure of
the entire array if another drive in the array fails. Additionally, it is possible that
noncorrectable drive errors can prevent a successful rebuild operation in some cases.
You can assign a single online spare drive to multiple arrays, or you can
choose to devote multiple drives to online spare duty for maximum
redundancy. When using a single online spare drive, be sure to assign it to
each array in the storage enclosure. The original online spare drive remains a
part of the array until the replacement drive is installed. Replacing an online
spare drive maintains a high level of fault tolerance.