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APPENDIX
RAID 10(1E)
RAID 10(1E) is a combination of RAID 0 and RAID 1, combining
stripping with disk mirroring. RAID Level 10 combines the fast
performance of Level 0 with the data redundancy of level 1. In
this configuration, data is distributed across several disk drives,
similar to Level 0, which are then duplicated to another set of
drive for data protection. RAID 10 has been traditionally imple-
mented using an even number of disks, some hybrids can use
an odd number of disks as well. Illustration is an example of a
hybrid RAID 10(1E) array comprised of five disks; A, B, C, D and
E. In this configuration, each strip is mirrored on an adjacent disk
with wrap-around. Areca RAID 10 offers a little more flexibility in
choosing the number of disks that can be used to constitute an
array. The number can be even or odd.
RAID 3
RAID 3 provides disk striping and complete data redundancy
though a dedicated parity drive. RAID 3 breaks up data into
smaller blocks, calculates parity by performing an exclusive-or
on the blocks, and then writes the blocks to all but one drive in
the array. The parity data created during the exclusive-or is then
written to the last drive in the array. If a single drive fails, data is
still available by computing the exclusive-or of the contents cor-
responding strips of the surviving member disk. RAID 3 is best
for applications that require very fast data- transfer rates or long
data blocks.
