Installation guide

Glossary
Manual No. 775007 G-5
PCI
Peripheral Component Interconnect – This is a high-performance, backplane
interface, expansion slot architecture that is found on PCs, Macintoshes, and
UNIX workstations. PCI is a standardized architecture that provides a high-
speed data path between peripherals and the CPU. PCI cards are portable
across hardware platforms with the help of various software drivers.
RAID
RAID stands for Redundant Array of Independent Disks. The DAC960
controllers implement this technology to connect up to 15 SCSI devices per
channel. Several different forms of RAID implementation have been
defined. Each form is usually referred to as a “RAID level.” All the RAID
levels supported by DAC960 Series controllers are shown below.
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 XOR redundancy.