PCWS 2015 Setup Guide - 2nd Edition 3-45
What’s Inside?
Installing Options
RAID Overview
The following discusses the various options available for using a RAID on the
PCWS 2015. With two drives available and RAID support included in the PCH
and BIOS, basic RAID Level 0 and 1 configurations are possible. The
following section provides consideration of each type, then goes on to describe
how to configure the BIOS to build a two-drive RAID.
RAID Level 0 - Striping (Performance)
Simple stripe sets are referred to as RAID Level 0. This configuration
provides improved performance and additional storage but no redundancy
or fault tolerance.
Failure of either disk destroys the array, and the likelihood of failure
increases with more disks in the array. With two drives, catastrophic data
loss is twice as likely compared to a single drive without RAID.
A single disk failure destroys the array because when data is written to a
RAID 0 volume, it is broken into a number of fragments called blocks. The
number of blocks is dictated by the stripe size, a configuration parameter
supplied when building the RAID. The blocks are written to each disk
simultaneously on the same sector. This allows smaller sections of the
entire chunk of data to be read from the drive in parallel, increasing
bandwidth. RAID 0 does not implement error checking, so should an error
occur, it is uncorrected.
RAID Level 1 - (Mirroring)
RAID Level 1 offers data security and limited fault tolerance by mirroring
identical data on two drives. This is often called a mirrored set.
The two drive array provides fault tolerance from single disk errors or
failures and the array will continue to operate as long as one drive is still
operating.
Increased read performance occurs when using a multi-threaded operating
system such as Windows 7 that supports split seeks, as well as a very small
reduction in performance when writing to the mirrored set.
A RAID 1 Mirrored Set is no Substitute for Regular Data Backups
Data may become damaged or destroyed without physical harm to
drive(s) on which they are stored. Examples include data becoming
overwritten by a system malfunction; files may be damaged or deleted
by user error or malice and not be noticed for days or weeks.
RAID 1 is also vulnerable to controller failure, and it may not be
possible to migrate the drives to new system board without data loss.
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