User's Manual

54 Understanding RAID Concepts
Table 3-1. RAID Level and Concatenation Performance Comparison
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.
Trans ac ti on
al 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
environment
s (large
records)
RAID 50 Good Very Good Fair Fair N + 2
(N = at
least 4)
Medium-
sized
transactional
or data-
intensive
uses
N = Number of physical disks
X = Number of RAID sets