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About RAID Levels
Striping (RAID 0)
Reads and writes sectors of data interleaved between multiple drives. When any disk member
fails, it affects the entire array. Performance is better than a single drive since the workload is
balanced between the array members.
This array type is for high performance systems. Identical drives are recommended for
performance as well as data storage efficiency. The disk array data capacity is equal to the
number of drive members times the smallest member capacity. For example, one 100 GB and
three 120 GB drives will form a 400 GB (4 x 100 GB) disk array.
Stripe Size - A value can be set from 16 KB to 128 KB sector size. The size can directly affect
performance. In the EasyBuild BIOS, the default is 64 KB.
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 IDE 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.
On the next reboot, the EasyBuild utility will display an error in the array and recommend
replacing the failed drive. Users should replace 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.
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Disk Drives
Data Mirror
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Disk Drives
WD SERIAL ATA RAID CONTROLLER
USER MANUAL
Data
Stripe
DISK ARRAY CONCEPTS - 7
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