NonStop System Glossary

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.
environmental monitoring unit (EMU)
An element that monitors the status of an enclosure, including the power, air temperature, or blower
status. The EMU detects problems and displays and reports these conditions to a user and the
controller. In some cases, the EMU implements corrective action.
environmental parameters
Subsystem Control Facility (SCF) session parameters set by default or by using various SCF
commands. The values associated with the environmental parameters can be examined using the
ENV command.
environment strings
For an Open System Services (OSS) process, a vector of strings of the form name = value that
contains information about the environment that the process runs in. Environment strings are
accessible to the process and are inherited by its child processes.
EPO
See emergency power off (EPO).
EPO connector
See emergency power-off (EPO) connector.
Epoch
The period beginning January 1, 1970, at 0 hours, 0 minutes, and 0 seconds Coordinated Universal
Time (UTC).
EPTRACE
A performance investigation tool for Open System Services (OSS) and Guardian environments. It
is designed to count, trace, locate, and provide a log of millicode-corrected misalignments in TNS
stumble events.
equipment grounding conductor
The conductor used to connect the non-current-carrying metal parts of equipment, raceways, and
other enclosures to the grounding electrode conductor at the facility’s main service entrance or at
the source of a separately derived power source.
errno
An external variable that contains the most recent error condition set by a C function.
error correction code (ECC)
A coding system that incorporates extra parity bits in order to detect errors.
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