Fault Tolerance And Drive Failure; Non-Fault-Tolerant (Raid 0) Logical Drive; Raid 1 (Mirroring) Logical Drive - Compaq RAID Array 4100 User Manual

F-2 Compaq StorageWorks RAID Array 4100 User Guide

Fault Tolerance and Drive Failure

Non-Fault-Tolerant (RAID 0) Logical Drive

RAID 1 (Mirroring) Logical Drive

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Compaq Insight Manager can detect failed drives remotely across a
network.
Problems such as reduced system performance or disk errors reported by the
operating system do not necessarily imply that a drive has or has not failed. If
drive failures or repeated errors are suspected, Compaq recommends running
the Array Diagnostic Utility on the system.
In the event of a drive failure, the condition of the logical drive will vary
depending upon the fault-tolerance method used. Since a single array of
physical drives can contain multiple logical drives with differing
fault-tolerance methods, conditions of each logical drive on the same array are
not necessarily the same. At any one time, if more drives are failed than the
fault-tolerance mode allows, fault tolerance is referred to as being
compromised and the condition of the logical drive can be referred to as
"failed." If a logical volume is failed, all requests from the operating system
will be rejected with unrecoverable errors.
Non-Fault-Tolerant (RAID 0) Logical Drives cannot sustain drive failures. If
any physical drive in the array is failed, the condition of all non-fault-tolerant
logical drives in the same array will also be "failed." This is because data is
striped across all drives in the array.
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Can sustain multiple drive failures as long as failed drives are not
mirrored to one another.
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Will be in a failed condition if any two failed drives are mirrored to one
another.
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Will be in a "regenerating" condition if at least one drive is failed, and
no failed drives are mirrored to one another.
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Will be in a "rebuilding" condition if a previously failed drive has been
replaced and the replacement drive is rebuilding. The volume may also
be in a rebuilding condition following a drive failure if a spare drive was
previously assigned and is rebuilding.