Advantech RAID-800S, Installation Reference Manual

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160 RAID-800S User's Manual
The RAID-800S subsystem supports RAID level 0, 1, 0+1, 3 and 5. The
following describes each of these levels.
A.1 RAID 0 (Striping)
Striping refers to the storing of a sequential block of incoming data
across multiple drives in a drive group. This is the striping technique. If
there are three drives in a drive group, the data will be separated into
blocks. Block one of the data will be stored on drive one, block two on
drive two and block three on drive three. Drive one will again be the
location of the next block (block four), then block five is stored on drive
two, block six on drive three, and so on. This method can significantly
increase disk system throughput, particularly for transferring large,
sequential data blocks.
A.2 RAID 1 (Mirroring)
Mirroring refers to the 100% duplication of data from one disk drive
onto another. Each disk contains the mirror image of the data on the
other drive.
A.3 RAID 0+1 (Striping and Mirroring)
Hard drives will be striped first, then mirrored. It requires at least 4 hard
drives and the total number of hard drives must always be even.
A.4 RAID 3 (Striping with One Parity Hard Drive)
RAID level 3 requires at least three SCSI drives, one of which is solely
used for storing parity information. It provides high transfer rate and
high availability at a lower cost than mirroring but its transaction
performance is poorer because all member disks operate in lockstep.