NonStop S-Series System Expansion and Reduction Guide

Glossary
G-Series Common Glossary
Glossary-26
downward compatibility
downward compatibility. The ability of a requester to operate with a server of an earlier
revision level. In this case, the requester is downward-compatible with the server, and
the server is upward-compatible with the requester. Contrast with upward compatibility
.
drive. See disk drive or tape drive.
dropout. A voltage loss of very short duration (that is, milliseconds).
DSC. See Dynamic System Configuration (DSC).
DSM. See Distributed Systems Management (DSM).
DSM/SCM. See Distributed Systems Management/Software Configuration Manager
(DSM/SCM).
DSV. See distribution subvolume (DSV).
DTE. See data terminal equipment (DTE).
dual inline memory module (DIMM). Small circuit boards carrying memory integrated
circuits, with signal and power pins on both sides of the board. A DIMM is different
from a single inline memory module (SIMM) in that the connections on each side of the
module connect to different chips, whereas the connections on both sides of a SIMM
connect to the same memory chip. This difference gives the DIMM a wider data path,
as more modules can be accessed at once.
dual-ported. The capability of a ServerNet adapter or peripheral device to receive data and
commands from two sources although only one source might have access at any
particular moment.
duplicate file descriptor. In the Open System Services (OSS) file system, a file descriptor
that refers to the same open file description as another file descriptor.
dynamic configuration file (DCF). An attachment file that is produced by the OSM and
TSM client software and accompanied by an incident report. The DCF contains a
snapshot of the system configuration, the state of the HP NonStop™ S-series server,
and outstanding alarms at the time that the incident report was issued. The DCF is
used by the service provider to avoid having to perform online discovery of the server
over dial-up telephone lines.
Dynamic Host Configuration Protocol (DHCP). An Internet protocol for automating the
configuration of computers that use TCP/IP. DHCP can automatically assign IP
addresses, deliver TCP/IP stack configuration parameters such as the subnet mask
and default router, and provide other configuration information such as the addresses
for printer, time, and news servers.
dynamic information. Information that represents the set of resources that actually exist in
the current configuration of an HP NonStop™ S-series server. Dynamic information is