EC See engineering change. ECKD See extended count key data.
eight pack
See disk pack.
electrostatic discharge (ESD)
An undesirable discharge of static
electricity that can damage equipment and
degrade electrical circuitry.
emergency power off (EPO)
A means of turning off power during an
emergency, usually a switch.
EMIF See ESCON multiple image facility.
enclosure
A unit that houses the components of a
storage subsystem, such as a control unit,
disk drives, and power source.
end of file
A coded character recorded on a data
medium to indicate the end of the
medium. On a count-key-data direct
access storage device, the subsystem
indicates the end of a file by including a
record with a data length of zero.
engineering change (EC)
An update to a machine, part, or program.
Enterprise Systems Architecture/390 (ESA/390)
An IBM architecture for mainframe
computers and peripherals. Processor
systems that follow the ESA/390
architecture include the ES/9000

®

family.
See also z/Architecture.
Enterprise Systems Connection (ESCON)
1) A zSeries computer peripheral interface.
The I/O interface uses zSeries logical
protocols over a serial interface that
configures attached units to a
communication fabric.
2) A set of IBM products and services that
provide a dynamically connected
environment within an enterprise.
EPO See emergency power off. ERDS See error-recording data set. ERP See error recovery procedure.
error-recording data set (ERDS)
On zSeries hosts, a data set that records
data-storage and data-retrieval errors. A
service information message (SIM)
provides the error information for the
ERDS.
error recovery procedure (ERP)
Procedures designed to help isolate and,
where possible, to recover from errors in
equipment. The procedures are often used
in conjunction with programs that record
information on machine malfunctions.
ESA/390
See Enterprise Systems Architecture/390.
ESCD See ESCON director.
ESCON
See Enterprise System Connection.
ESCON channel
A zSeries channel that supports ESCON
protocols.
ESCON director (ESCD)
An I/O interface switch that allows the
interconnection of multiple ESCON
interfaces in a distributed-star topology.
ESCON host systems
zSeries hosts that attach to the DS8000
with an ESCON adapter. Such host
systems run on operating systems that
include MVS, VSE, TPF, or versions of
VM.
ESCON multiple image facility (EMIF)
For zSeries, a function that enables
LPARs to share an ESCON channel path
by providing each LPAR with its own
channel-subsystem image.
EsconNet
In the DS Storage Manager, the label on a
pseudo host icon that represents a host
connection that uses the ESCON protocol
and that is not completely defined on the
DS8000. See also pseudo host and
access-any mode. ESD See electrostatic discharge.
eserver
See IBM e(logo)server.
ESSNet
See IBM TotalStorage Enterprise Storage
Server Network.
extended binary-coded decimal interchange
code (EBCDIC)
An IBM-developed coding scheme used to
represent various alphabetic, numeric, and

Glossary 333