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power failure, the BBU can hold data in the cache for a
certain amount of time. Once power is restored the data can
be saved to a disk.
Benchmarks
A set of conditions or criteria against which a product or
system is measured. Computer trade magazine laboratories
frequently test and compare several new computers or
computer devices against the same set of application
programs, user interactions, and contextual situations. The
total context against which all products are measured and
compared is referred to as the benchmark. Programs can be
specially designed to provide measurements for a
particular operating system or application.
Berkeley RAID Levels
A family of disk array protection and mapping techniques
described by Garth Gibson, Randy Katz, and David
Patterson in papers written while they were performing
research into I/O systems at the University of California at
Berkeley. There are six Berkeley RAID levels, usually
referred to as RAID Level 0 through RAID Level 5. See
also RAID Levels.
BIOS
Basic Input/Output System, software that determines what
a computer can do without accessing programs. The BIOS
contains all the code required to control the keyboard,
screen, drives, serial communications, and other functions.
Usually the BIOS is built into a ROM chip installed on the
motherboard so that the BIOS will always be available and
not affected by disk failure. Sometimes the BIOS is
recorded on a flash memory chip.
BIOS Configuration Utility
BIOS-based Configuration Utility, a utility program
sequence used, upon powerup, for configuring various
hardware elements in a system.
Booting (or Bootstrapping)
Loading operating system code and other basic software
from a disk or other storage device to help a computer start.
Bridge RAID Controller
A device appearing as a single ID in a SAN, but which
bridges to multiple devices, typically used to control
external RAID subsystems (compare to Internal PCI-based
226
RAID subsystems, see Internal RAID Controller). A bridge
RAID controller is often referred to as an External RAID
Controller.
Burst Data Rate
The speed at which a specific amount of data is sent or
received in intermittent operations (compare to Sustained
Data Transfer Rate).
Bus
A set of conductors that connect the functional units in a
computer and are the channels through which data is
transferred. There are several types of bus channels,
including serial, parallel, PCI, ISA, EISA, and MCA. See
also I/O Bus.
C
Cache
A temporary storage area for frequently accessed or
recently accessed data. Cache is used to speed up data
transfer to and from a disk. See also Caching.
Cache Flush
Refers to an operation where all unwritten blocks in a
Write-Back Cache are written to the target disk. This
operation is necessary before powering down the system.
Cache Line Size
Represents the size of the data "chunk" that will be read or
written at one time, and is set in conjunction with stripe
size. Under RAID EzAssist™ , the segment size (also
known as Segment Size) should be based on the stripe size
you selected. The default segment size for RAID
controllers is 8K.
Caching
Allows data to be stored in a pre-designated area of a disk
or RAM. Caching speeds up the operation of RAID
systems, disk drives, computers and servers, or other
peripheral devices. See also Cache.
CD-ROM
Compact Disk-Read Only Memory, a removable read-only
storage device, similar to an audio compact laser disk,
holding up to 640MB of data.
Spheras Storage Director Installation & User Guide
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