Users Guide

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
RAID
Level
Data
Availability
Read Performance
Write Performance
Rebuild
Performance
Minimum Disks
Required
Suggested Uses
Concatenation
No gain
No gain
No gain
N/A
1 or 2 depending
on the controller.
More cost efficient than redundant
RAID levels. Use for noncritical
data.
RAID 0
None
Very Good
Very Good
N/A
N
Noncritical data
RAID 1
Excellent
Very Good
Good
Good
2N
(N = 1)
Small databases, database logs,
critical information
RAID 5
Good
Sequential reads: good.
Transactional reads: Very
good
Fair, unless using
write-back cache
Fair
N + 1
(N = at least two
disks)

Databases and other read-
intensive transactional uses
RAID 10
Excellent
Very Good
Fair
Good
2N x X
Data-intensive environments
(large records)
RAID 50
Good
Very Good
Fair
Fair
N + 2
(N = at least 4)
Medium-sized transactional or
data-intensive uses
RAID 6
Excellent
Sequential reads: good.
Transactional reads: Very
good
Fair, unless using
write-back cache
Poor
N + 2
(N = at least two
disks)

Critical information. Databases
and other read-intensive
transactional uses.
RAID 60
Excellent
Very Good
Fair
Poor
X x (N + 2)
(N = at least 2)
Critical information. Medium-sized
transactional or data-intensive
uses.
N = Number of physical disks
X = Number of RAID sets