HP LH4r HP NetServer FCArray Assistant - Installation and User Guide - Page 158

RAID stands for Redundant Array of Independent Disks. Several different forms

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Appendix B Glossary Rebuild: A disk drive is in a "rebuild" state... While it is in the process of being rebuilt. During this process, data is regenerated and written to the disk drive. This state is sometimes referred to as "Write-Only" (WRO). RAID RAID stands for Redundant Array of Independent Disks. Several different forms of RAID implementation have been defined. Each form is usually referred to as a "RAID level." The basic RAID levels supported by disk array controllers are described under RAID Levels in the following topics. 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 Controller The controller acts as a bridge between host channels and drive channels and implements the RAID function. On the drive channels, the controller acts as an initiator. The host channel ports are implemented as target IDs; with logical drives presented as LUNs under the target IDs. RAID Levels HP supports four RAID Advisory Board-approved RAID levels (RAID 0, RAID 1, RAID 3, and RAID 5) and several special RAID levels (RAID 0+1, RAID 00, RAID 10, RAID 30, RAID 50, 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% 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. 152

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Appendix B
Glossary
152
Rebuild: A disk drive is in a “rebuild” state...
While it is in the process of being rebuilt. During this process, data is
regenerated and written to the disk drive. This state is sometimes referred
to as "Write-Only" (WRO).
RAID
RAID stands for Redundant Array of Independent Disks. Several different forms
of RAID implementation have been defined. Each form is usually referred to as a
"RAID level." The basic RAID levels supported by disk array controllers are
described under RAID Levels in the following topics.
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 Controller
The controller acts as a bridge between host channels and drive channels and
implements the RAID function. On the drive channels, the controller acts as an
initiator. The host channel ports are implemented as target IDs; with logical drives
presented as LUNs under the target IDs.
RAID Levels
HP supports four RAID Advisory Board-approved RAID levels (RAID 0, RAID
1, RAID 3, and RAID 5) and several special RAID levels (RAID 0+1, RAID 00,
RAID 10, RAID 30, RAID 50, 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% 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.