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Appendix A : RAID Levels Tutorial
FASTORA DAS-315SA DAS Subsystem supports RAID levels 0, 1, 3, 5 and
0+1. This tutorial will give you a brief look of the RAID (Redundant Array of
Inexpensive Disks) technology.
This appendix covers the following topics:
A.1 RAID Fundamentals
RAID
0
RAID
1
RAID
2
RAID
3
RAID
4
RAID
5
Summary
Table
A.1 RAID Fundamentals
RAID (
R
edundant
A
rray of
I
ndependent
D
isks) is a series of storage
technologies described in 1987 by three researchers from University of
California at Berkeley: David Patterson, Garth Gibson and Randy Katz. RAIDs
were conceived to overcome the data reliability problems associated with disk
storage subsystems while increasing various performance aspects.
Here we put a description of how each type of RAID operates, plus its
strengths and weaknesses. An unavoidable drawback to all large groups of
disk drives, although disk MTBF figures range up to 250,000 hours or five
years, is a large number of “maintenance incidents”. Because of redundancy
schemes, these “incidents” in a RAID do not normally result in any loss of data
or even access to the data. Stated another way, there will be failures of disks
over the lifetime of a large RAID disk subsystem, but it is unlikely that there will
