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

Glossary
318 HP StorageWorks HSG60 and HSG80 Array Controller and Array Controller Software
Command Line Interface Reference Guide
dirty data
The writeback cached data that has not been written to storage media, even though the host
operation processing the data has completed.
disaster tolerance
The ability to resume data center operations shortly after a significant event occurs at the
primary data center. The ability to restart processing can require an alternate data center,
with current copies of critical data in a usable state.
disk inline exerciser
See DILX
DMA
Direct Memory Access.
DOC
DWZZA-on-a-chip. An SYM53C120 SCSI bus extender chip used to connect a SCSI bus
in one enclosure to the corresponding SCSI bus in another enclosure.
driver
A hardware device or a program that controls or regulates another device. For example, a
device driver is a driver developed for a specific device that allows a computer to operate
with the device, such as a printer or a disk drive.
dual data link
See DDL
dual-redundant configuration
A controller configuration consisting of two active controllers operating as a single
controller. If one controller fails, the other controller assumes control of the failing
controller devices.
dual-simplex
A communications protocol that allows simultaneous transmission in both directions in a
link, usually with no flow control.
DUART
Dual Universal Asynchronous Receiver and Transmitter. An integrated circuit containing
two serial, asynchronous transceiver circuits.
DWZZA
An HP StorageWorks SCSI-bus-signal converter used to connect 8-bit single-ended devices
to hosts with 16-bit differential SCSI adapters. This converter extends the range of a
single-ended SCSI cable to the limit of a differential SCSI cable. See also SCSI bus signal
converter.