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Introduction
Mirroring (RAID 1)
Mirroring refers to the duplication of data on two disk drives. Each disk contains
a copy of the data on the other drive.
Striping with Dedicated Parity Drive (RAID 3)
RAID level 3 the data is striped in blocks across several physical drives and parity
data on a separate drive. The benefits are that this level uses a fraction of the disk
space required by RAID level 1 to achieve data redundancy. It provides good
performance for transaction processing applications because each drive can read
and write independently. Should a data drive fail, the controller continues to
allow reads and writes independently to the remaining data drives, while
calculating and rebuilding the missing information on the standby drive using the
parity data.
Striping with Mirroring (RAID 0+1)
RAID 0+1 is a combination of RAID 0 (striping) and RAID 1 (mirroring).
The advantages of RAID 0+1 are fully mirrored data and better performance
than RAID 1. The disadvantage of RAID 0+1 is its 50% utilization capacity.
Striping with Parity (RAID 5)
Striping with parity provides complete data redundancy and requires only a
fraction of the storage capacity required for mirroring.
In a system configured under RAID 5 (requires at least three drives) all data and
parity blocks are divided between the dries in such a way that if any single drive
is removed (or fails), the data on the missing drive can be reconstructed onto a
standby drive using the data on the remaining drives.
JBOD
JBOD is an acronym for Just a Bunch of Drives. The disk drives function
independent of one another, just as they would on a non-RAID controller.
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Supported RAID Levels
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