INTRODUCTION TO RAID 5 ARRAYS
Definition of a RAID 5 Array
A RAID 5 array uses at least three disks
and stripes information at the byte level across the member
disks. Parity data is also written across each member disk to
allow the RAID data to be recovered in the event of a disk
failure.
Different Ways a RAID 5 Array Can
Be Set Up
A RAID 5 array can be set up as a software
RAID using special software or as a hardware RAID using a RAID
controller.
A software RAID is generally either set up
using standalone software or using RAID software which is built
into an operating system such as Windows 2003 Server. A software
RAID uses the CPU and memory of the computer on which it is
installed. This can slow down other applications on that
computer. This also makes the software RAID vulnerable to
failure due to problems with the host computer. A hardware RAID
uses a RAID controller which handles array duties thus there is
no strain on the host computer's CPU and memory.
Applications Best Suited for RAID
5
Since RAID 5 offers better read
performance than write performance, it is best suited for
read-oriented applications such as web, intranet, and email
servers. It could also be suited for databases as long as there
is more reading than writing. With RAID 5, writes are slowed
down because the array must write parity data to the disks.
Advantages and Disadvantages of
RAID 5 Arrays
There are several advantages from a RAID 5
array. Since a RAID 5 writes parity data to each of the member
disks, a RAID 5 can sustain the failure of one disk. The parity
data allows the RAID to be recovered. Another advantage of RAID
5 is that it is fairly cost-effective considering the amount of
fault tolerance it provides. Finally, RAID 5 offers a good rate
of reads to the member disks. Some disadvantages of RAID 5 are
that it offers slower writes as it must write parity data in
addition to regular data. It can also be expensive to implement
as it requires special hardware.
Conclusion
Overall, RAID 5 offers excellent fault
tolerance without wasting drive space. It also offers a high
read performance making it suitable for a wide variety of
applications. More information about RAID 5 arrays can be found
on our
RAID 5 Recovery page.
