Installation guide

Chapter 1. Introduction
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1.2.5 RAID 5
RAID 5 is sometimes called striping with parity at byte level. In RAID 5, the parity
information is written to all of the drives in the controllers rather than being
concentrated on a dedicated parity disk. If one drive in the system fails, the
parity information can be used to reconstruct the data from that drive. All drives
in the array system can be used for seek operations at the same time, greatly
increasing the performance of the RAID system. This relieves the write
bottleneck that characterizes RAID 4, and is the primary reason that RAID 5 is
more often implemented in RAID arrays.
1.2.6 RAID 6
RAID 6 provides the highest reliability. It is similar to RAID 5, but it performs two
different parity computations or the same computation on overlapping subsets
of the data. RAID 6 can offer fault tolerance greater than RAID 1 or RAID 5 but
only consumes the capacity of 2 disk drives for distributed parity data. RAID 6 is
an extension of RAID 5 but uses a second, independent distributed parity
scheme. Data is striped on a block level across a set of drives, and then a
second set of parity is calculated and written across all of the drives.