Open SCSI Integrator's Manual for NonStop S-Series Servers

Glossary
Open SCSI Integrator’s Manual for NonStop Servers—422988-002
Glossary-6
Distributed Systems Management (DSM)
Distributed Systems Management (DSM). A set of tools used to manage NonStop systems
and Expand networks.
double-high ServerNet adapter. A ServerNet adapter that occupies an entire ServerNet
adapter slot in a Himalaya S-series server. Contrast with single-high ServerNet adapter
.
double-high stack. A stack that includes a base, a frame, and two system enclosures.
Contrast with single-high stack
.
downtime. Time during which a NonStop system is not capable of doing useful work
because of a planned or unplanned outage. From the end user’s perspective, downtime is
any time a needed application is not available.
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
.
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.
E4SA. See Ethernet 4 ServerNet adapter (E4SA)
.
electromagnetic interference (EMI). Interference caused by electromagnetic radiation.
electrostatic discharge (ESD) protection kit. A kit containing an antistatic mat and a
wriststrap with a cable and clip. A service provider or customer wears the wriststrap
while performing maintenance procedures inside an enclosure. The wriststrap and cable
contain grounding wires so that when the clip is attached to a metal object, such as the
enclosure, the person wearing the wriststrap is grounded and any static electricity
incurred during the procedure is discharged safely to the enclosure instead of to
electrical components within the enclosure.
emergency power-off (EPO) connector. A two-pin connector on the service side of an
enclosure that allows an external signal to disable the batteries in the enclosure during
emergency conditions. A cable is attached from the connector to a relay band or push
button typically located near the door of a computer room. Pushing the EPO button
removes power from all computer equipment in the room. The EPO connectors prevent
the batteries from powering the server after power is removed. EPO capabilities are
required in the United States when a server is installed in a computer room designed to
comply with the special construction and fire protection provisions of the United States’
national electrical code (or at other sites as required by local regulations.)