User Manual

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If disk drives of different capacities are used, there will also be unused
capacity on the larger drives.
Because RAID 0 does not offer Fault Tolerance, meaning that you cannot
recover your data after a disk drive failure, we do not recommend a RAID 0
Volume for your unit.
RAID 0 Volumes on this unit consist of one or more disk drives.
RAID 1 – Mirror
When a RAID Volume is mirrored, identical data is written to a pair of disk
drives, while reads are performed in parallel. The reads are performed using
elevator seek and load balancing techniques where the workload is distributed
in the most efficient manner. Whichever drive is not busy and is positioned
closer to the data will be accessed first.
With RAID 1, if one disk drive fails or has errors, the other mirrored disk drive
continues to function. This is called Fault Tolerance. Moreover, if a spare disk
drive is present, the spare drive will be used as the replacement drive and data
will begin to be mirrored to it from the remaining good drive.
The RAID Volume’s data capacity equals the smaller disk drive. For example,
a 100 GB disk drive and a 120 GB disk drive have a combined capacity of 100
GB in a mirrored RAID Volume.
If disk drives of different capacities are used, there will also be unused
capacity on the larger drive.