HP 3000 Enterprise Virtual Array - Manual (Page 140)

array controller See controller .
asynchronous Events scheduled as the result of a signal requesting the event or that which is
without any specified time relation.
audible alarm The Environmental Monitoring Unit (EMU) alarm that sounds when there is a
drive enclosure element condition report. The audible alarm can be muted
or disabled.
backplane An electronic printed circuit board that distributes data, control, power, and
other signals to element connectors.
bad block A data block that contains a physical defect.
bad block replace-
ment
A replacement routine that substitutes defect-free disk blocks for those found to
have defects. This process takes place in the controller and is transparent to
the host.
bail lock Part of the power supply AC receptacle that engages the AC power cord
connector to ensure that the cord cannot be accidentally disconnected.
baud The maximum rate of signal state changes per second on a communication
circuit. If each signal state change corresponds to a code bit, then the baud
rate and the bit rate are the same. It is also possible for signal state changes
to correspond to more than one code bit so the baud rate may be lower than
the code bit rate.
bay The physical location of an element, such as a drive, I/O module, EMU or
power supply in a drive enclosure. Each bay is numbered to define its location.
bidirectional Also called Bi-Di. The movement of optical signals in opposite directions through
a common fiber cable such as the data flow path typically on a parallel printer
port. A parallel port can provide two-way data flow for disk drives, scanning
devices, FAX operations and even parallel modems.
block Also called a sector. The smallest collection of consecutive bytes addressable
on a disk drive. In integrated storage elements, a block contains 512 bytes of
data, error codes, flags, and the block address header.
blower A variable speed airflow device that pulls air into an enclosure or element. It
usually pulls air in from the front and exhausts the heated air out the rear.
cabinet An alternate term used for a rack.
cable assembly A fiber optic cable that has connectors installed on one or both ends. General
use of these cable assemblies includes the interconnection of multimode fiber
optic cable assemblies with either LC or SC type connectors.
• When there is a connector on only one end of the cable, the cable assembly
is referred to as a pigtail.
• When there is a connector on each end of the cable, the cable assembly
is referred to as a jumper.
CAC Corrective Action Code. An HP Command View EVA graphical user interface
(GUI) display component that defines the action required to correct a problem.
See also read cache , write cache , and mirrored cache .
cache High-speed memory that sets aside data as an intermediate data buffer between
a host and the storage media. The purpose of cache is to improve performance.
cache battery A rechargeable unit mounted within a controller enclosure that supplies back-up
power to the cache module in case of primary power shortage.
140 Glossary