User's Manual

Understanding RAID Concepts 53
Comparing RAID Level and Concatenation
Performance
The following table compares the performance characteristics associated with
the more common RAID levels. This table provides general guidelines for
choosing a RAID level. Evaluate your specific environment requirements
before choosing a RAID level.
NOTE: The following table does not show all RAID levels supported by Storage
Management. For information on all RAID levels supported by Storage
Management, see
Choosing RAID Levels and Concatenation .
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.
Transaction
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
N = Number of physical disks
X = Number of RAID sets