IBM Z9 Planning Manual page 260

domain. (1) That part of a computer network in which
the data processing resources are under common
control. (T) (2) In SNA, a system services control point
(SSCP) and the physical units (PUs), logical units (LUs),
links, link stations, and all associated resources that the
SSCP has the ability to control by means of activation
requests and deactivation requests.
dynamic connection. In an ESCON Director, a
connection between two ports, established or removed
by the ESCD and that, when active, appears as one
continuous link. The duration of the connection depends
on the protocol defined for the frames transmitted
through the ports and on the state of the ports.
dynamic reconfiguration. Pertaining to a processor
reconfiguration between a single-image (SI)
configuration and a physically partitioned (PP)
configuration when the system control program is active.
dynamic storage reconfiguration. A PR/SM LPAR
function that allows central or expanded storage to be
added or removed from a logical partition without
disrupting the system control program operating in the
logical partition.
E
element. A major part of a component (for example,
the buffer control element) or a major part of a system
(for example, the system control element).
environmental error record editing and printing
program (EREP). The program that makes the data
contained in the system recorder file available for further
analysis.
EREP. Environmental error record editing and printing
program.
error. A discrepancy between a computed, observed,
or measured value or condition and the true, specified,
or theoretically correct value or condition. (I) (A)
ESA/390. Enterprise Systems Architecture/390.
ESCD. Enterprise Systems Connection (ESCON)
Director.
ESCM. Enterprise Systems Connection Manager.
ESCON. Enterprise Systems Connection.
ESCON channel. A channel having an Enterprise
Systems Connection channel-to-control-unit I/O interface
that uses optical cables as a transmission medium.
ESCON Director (ESCD). A device that provides
connectivity capability and control for attaching any two
links to each other.
ESCON environment. The data processing
environment having an Enterprise Systems Connection
D-4
PR/SM Planning Guide
channel-to-control-unit I/O interface that uses optical
cables as a transmission medium.
ESCON Manager (ESCM). A licensed program that
provides host control and intersystem communication
capability for ESCON Director connectivity operations.
ETR. External time reference.
event. (1) An occurrence or happening. (2) An
occurrence of significance to a task; for example, the
completion of an asynchronous operation, such as an
input/output operation.
expanded storage. Optional high-speed storage that
transfers 4 KB pages to and from central storage.
extent. (1) Continuous space on a disk or diskette that
is occupied by or reserved for a particular data set, data
space, or file. (2) A set of consecutively addressed
tracks that a channel program can access. The limits of
an extent are defined by specifying the addresses of the
first and last tracks in the extent.
F
failure. An uncorrected hardware error.
Note: Failures are either recoverable or not recoverable
by the software or the operator. The operator is
always notified when failures occur. Usually,
system recovery occurs through a hardware
reconfiguration. If this is not possible, recovery
requires a repair of the failed hardware.
FCC. Federal Communications Commission.
feature. A part of an IBM product that may be ordered
separately by the customer. A feature is designated as
either special or specify and may be designated also as
diskette-only.
Federal Communications Commission (FCC). A
board of commissioners appointed by the President
under the Communications Act of 1934, having the
power to regulate all interstate and foreign
communications by wire and radio originating in the
United States.
G
GB. Gibabyte.
GMT. Greenwich mean time.
guest. In interpretive execution mode, the interpreted
or virtual machine as opposed to the real machine (the
host).