HP StorageWorks HSG60 and HSG80 Array Controller and Array Controller Software Command Line Interface Reference Guide (EK-G80CL-RA. C01, March 2005)

Glossary
336 HP StorageWorks HSG60 and HSG80 Array Controller and Array Controller Software
Command Line Interface Reference Guide
uninterruptible power supply
See UPS
unit
A container made accessible to a host. A unit can be created from a single disk drive. A unit
can also be created from a more complex container such as a RAIDset. See also target;
target ID number.
unwritten cached data
Sometimes called unflushed data. See also dirty data.
UPS
Uninterruptible power supply. A battery-powered power supply guaranteed to provide
power to an electrical device in the event of an unexpected interruption to the primary
power supply. Uninterruptible power supplies are usually rated by the amount of voltage
supplied and the length of time the voltage is supplied.
VHDCI
Very High-Density-Cable Interface. A 68-pin interface that is required for Ultra SCSI
connections.
virtual terminal
A software path from an operator terminal on the host to the controller CLI, sometimes
called a host console. The path can be established via the host port on the controller or via
the maintenance port through an intermediary host. See also maintenance terminal.
VTDPY
Virtual terminal display. A utility that allows viewing of specific informational displays
using CLI commands.
wide Ultra SCSI
Fast-20 on a Wide SCSI bus.
World Wide Name
A unique 64-bit number assigned to a subsystem by the Institute of Electrical and
Electronics Engineers (IEEE) and set by DIGITAL manufacturing before shipping. Also
called node ID within the CLI.
write hole
The period of time in a RAID level 1 or RAID level 5 write operation an opportunity
emerges for undetectable RAIDset data corruption. Write holes occur under conditions such
as power outages, where the writing of multiple members can be abruptly interrupted. A
battery backed-up cache design eliminates the write hole because data is preserved in cache
and unsuccessful write operations can be retried.