Promise Technology FastTrak66 Anwenderhandbuch Seite 52

Manual EN 05-08-1999 11:30 Pagina 48
Understanding Disk Array Concepts
If one of the mirrored drives suffers a mechanical failure (e.g. spindle failure)
or does not respond, the remaining drive will continue to function. This is
called Fault Tolerance. If one drive has a physical sector error, the mirrored
drive will continue to function.
On the next reboot, the FastBuildTM utility will display an error in the array
and recommend to replace the failed drive. Users may choose to continue using
their PC, however Promise recommends replacing the failed drive as soon as
possible. See Chapter 4 for a functional description.
Due to redundancy, the drive capacity of the array is half the total drive
capacity. For example, two 1GB drives that have a combined capacity of 2GB
would have 1GB of usable storage. With drives of different capacities, there
may be unused capacity on the larger drive.
Spare Drive -- Under a RAID 1 setup, an extra "hot spare" drive can be atta-
ched to the FastTrak66 and not assigned to the array. In this case, it will be put
on standby. This drive will be activated to replace a failed drive that is part of
the mirrored array. A rebuild is performed automatically in the background to
mirror the good drive onto the spare. At a later time, the system can be powe-
red off and the failed drive can be physically removed and replaced. Spare dri-
ves must be the same or larger capacity than the smallest array member.
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