NonStop NS-Series Servers Site Preparation (H06.03+)

Glossary
HP Integrity NonStop NS-Series Site Preparation Guide—527836-005
Glossary-3
electromagnetic interference (EMI)
electromagnetic interference (EMI). Forms of conducted or radiated interference that
might appear in a facility as either normal or common-mode signals. The frequency of
the interference can range from the kilohertz to gigahertz range. However, the most
troublesome interference signals are usually found in the kilohertz to low megahertz
range. At present, the terms electromagnetic interference and radio frequency
interference (RFI) are usually used interchangeably.
emergency power off (EPO). Describes equipment used to automatically disconnect all
electrical power to connected equipment if an emergency occurs. A computer room’s
main EPO system shuts off all room equipment (except for lighting and fire-sensor
equipment) if a fire occurs. An equipment zone EPO shuts off power to all connected
computer equipment if the EPO switch is activated.
emergency power-off (EPO) connector. A two-pin connector on the service side of an HP
NonStop™ S-series system 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 and prevents 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.)
EMI. See electromagnetic interference (EMI).
Enterprise Storage System (ESS). A collection of magnetic disks, their controllers, and the
disk cache in a stand-alone cabinet or cabinets. These disks are configured by an
attached console and presented to the attached server as logical volumes that can be
a fraction of a physical volume or can span volumes.
EPO. See emergency power off (EPO).
EPO connector. See emergency power-off (EPO) connector
.
ESS. See Enterprise Storage System (ESS)
.
Ethernet. A local area network (LAN) that uses the carrier sense multiple access with
collision detection (CSMA/CD) access method on a bus topology and is the basis for
the IEEE 802.3 standard.
fan. A component that circulates air into the enclosure to help maintain optimal
temperature.
fault tolerance. The ability of a computer system to continue processing despite the failure
of any single software or hardware component within the system.
feeder circuit. The circuit conductors installed between the facility’s main service entrance
and the power distribution panels (PDPs) that supply the branch circuits.