HP D5970A - NetServer - LCII Installation And User Manual page 159

Appendix B
Level 5
Data is "striped" across several physical drives. For data redundancy,
drives are encoded with rotated XOR redundancy.
Level 0+1
Combines RAID 0 striping and RAID 1 mirroring. This level provides
redundancy through mirroring.
Levels 00, 10, 30, and 50
Multi-layer RAID levels, which span RAID levels 0, 1, 3, and 5 by striping
data across, drive groups (RAID Drives).
JBOD
Sometimes referred to as "Just a Bunch of Disks." Each drive is operated
independently like a normal disk drive, or drives may be spanned and seen
as a single drive. This level does not provide data redundancy.
NOTE The host operating system drivers and software utilities remain
unchanged regardless of the level of RAID installed. The
controller makes the physical configuration and RAID level
implementation transparent to the host operating system.
RAID Operation
RAID Controllers use the host ports to connect to one or more Host Bus Adapters
in one or more host computer systems.
Depending on the model and configuration of the controller, there may be from
one to four host ports. Each configured logical drive consumes a particular
bus-target ID LUN on the host system. Multiple sets of disk drives are connected
to the controller via its drive channels. There may be as many as six drive
channels, depending on the controller model and configuration.
In duplex, or Active/Active mode, two identical RAID Controllers are connected
to the same hosts via their host ports, to the same drives via their drive channels,
and to each other via a special hardware link for heartbeat sensing. This forms a
redundant controller system. The two controllers work together handling data
traffic and mirror the write data in each other's cache memory. If one of the
controllers fails or otherwise becomes non-operational, the surviving controller
takes over its responsibilities with no loss of data.
Glossary
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