Promise Technology FastTrak TX2000 User Manual page 50

FastTrak TX2000™ Series User Manual
Mirroring (RAID 1)
Writes duplicate data on to a pair of drives while reads are performed in parallel. ATA RAID 1 is
fault tolerant because each drive of a mirrored pair is installed on separate IDE channels. 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.
RAID 1 (M irroring)
TM
On the next reboot, the FastBuild 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 page 27, "Rebuilding A
Mirrored Array", for a functional description.
Due to redundancy, the drive capacity of the array is half the total drive capacity. For example,
two 100 GB drives that have a combined capacity of 200 GB would have 100 GB of usable
storage. With drives of different capacities, there may be unused capacity on the larger drive.
Using a Spare Drive
Under a RAID 1 setup, an extra "hot spare" drive (a third drive on FastTrak TX2000) can be
attached to the FastTrak TX2000 and not assigned to the array. Such a drive will be activated
to replace a failed drive that is part of a mirrored array. A rebuild is performed automatically in
the background to mirror the good drive data on to the spare.
At a later time, the system can be powered off and the failed drive can be physically removed
and replaced. Spare drives must be the same or larger capacity than the smallest array
member.
NOTE: Due to IDE limitations when drives are in a Master/Slave configuration, if the drive that
fails is on the same channel as the "spare" drive, there is a possibility that the "spare" drive will
fail to be recognized by the system.
Striping/Mirror (RAID 0+1)
A combination of both above array types. It can increase performance by reading and writing
data in parallel while protecting data with duplication. A minimum of four drives needs to be
46