Installation guide

Glossary
Manual No. 775064 G-5
The appropriate RAID level for a system is selected by the system manager
or integrator. This decision will be based on which of the following are to be
emphasized:
Disk Capacity
Data Availability (redundancy or fault tolerance)
Disk Performance
RAID Levels
The disk array controllers monitored by this utility support four RAID
Advisory Board-approved (RAID 0, RAID 1, RAID 3, RAID 5) and two
special RAID levels (RAID 0+1, and JBOD).
Level 0. Block “striping” across multiple drives is provided, yielding higher
performance than is possible with individual drives. This level does not
provide any redundancy.
Level 1. Drives are paired and mirrored. All data is 100 percent duplicated
on a drive of equivalent size.
Level 3. Data is “striped” across several physical drives. Maintains parity
information which can be used for data recovery.
Level 5. Data is “striped” across several physical drives. For data
redundancy, drives are encoded with rotated parity.
Level 0+1. Combines RAID 0 striping and RAID 1 mirroring. This level
provides redundancy through mirroring. (Mylex RAID 6)
JBOD. Sometimes referred to as “Just a Bunch of Drives.” Each drive is
operated independently like a normal disk controller, or drives may be
spanned and seen as a single drive. This level does not provide data
redundancy. (Mylex RAID 7)
Level 10. Combines RAID 0 striping and RAID 1 mirroring spanned across
multiple drive groups (super drive group). This level provides redundancy
through mirroring.
Level 30. Data is “striped” across multiple drive groups (super drive group).
Maintains parity information which can be used for data recovery.
Level 50. Data is “striped” across multiple drive groups (super drive group).
For data redundancy, drives are encoded with rotated parity.