Installation guide

Chapter 1. Introduction
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1.2.2 RAID 1
RAID 1 also known as “disk mirroring”, data written to one disk drive is
simultaneously written to another disk drive. Read performance may be
enhanced if the array controller can parallel accesses both members of a
mirrored pair. During writes, there will be a minor performance penalty when
compared to writing to a single disk. If one drive fails, all data (and software
applications) are preserved on the other drive. RAID 1 offers extremely high
data reliability, but at the cost is doubling the required data storage capacity.
1.2.3 RAID 10(1E)
RAID 10(1E) is a combination of RAID 0 and RAID 1, combing 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 implemented 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.