Promise Technology FastTrak SX4000 Lite User Manual download pdf (Page 50)

FastTrak S150 SX4 / SX4000 / SX4000 Lite User Manual

Mirroring (RAID 1)

Writes duplicate data on to a pair of drives while reads are performed in parallel.

RAID 1 is fault tolerant because each drive of a mirrored pair is installed on

separate controller channels. If one of the mirrored drives suffers a mechanical

failure (for example, 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.

Disk Drives

Data Mirror

Figure 15. RAID 1 copies the data from one drive to the other

On the next reboot, the FastBuild™ Utility will display an error in the array and

recommend replacing the failed drive. Users may choose to continue using their

PC, however Promise recommends replacing the failed drive as soon as

possible.

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. You can

attach a third drive to the FastTrak S150 SX4 or SX4000 / SX4000 Lite without

assigning it to the array. Such a drive will be activated to replace a failed drive

that is part of a mirrored array. A rebuild takes place 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.

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Promise Technology FastTrak SX4000 Lite User Manual Page 50