User guide

Recovering From Hard Drive Failure
■ Will be in a “regenerating” condition if at least one drive is failed, and
no failed drives are mirrored to one another.
■ 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.
In any RAID 1 logical drive on the RA4000 having N physical drives in the
array (not including spare drives), the first N/2 physical drives are mirrored in
consecutive order to the second N/2 physical drives. When determining the
order, number each drive in the array by increasing IDs on the first SCSI bus,
followed likewise by drives on the second SCSI bus.
■ Can sustain a single drive failure. The logical drive will be in a
regenerating condition if one drive is failed.
■ Will be in a failed condition if more than one drive is failed.
■ 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.
In the event of a drive failure, if a spare drive is assigned and available, it acts
as an immediate replacement for the failed drive. Data is automatically
reconstructed from the remaining drives in the volume and written to the spare
drive via the Automatic Data Recovery process. Once the spare drive is
completely built, the logical drive is again running at full fault tolerance, and
is then able to sustain another subsequent drive failure. Note, however, that if
another drive were to fail before the spare drive is completely built, the spare
drive cannot prevent failure of the entire logical drive.