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services that provide a dynamically connected
environment within an enterprise.
EPO. See emergency power off .
ERP. See error recovery procedure .
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 Systems Connection .
ESCON director (ESCD). An I/O interface switch that
allows the interconnection of multiple ESCON interfaces
in a distributed-star topology.
ESCON multiple image facility (EMIF). In the
ESA/390 architecture, a function that allows LPARs to
share an ESCON channel path by providing each LPAR
with its own channel-subsystem image.
ESD. See electrostatic discharge .
ESS Specialist. See StorWatch Enterprise Storage
Server Specialist .
extended binary-coded decimal interchange code
(EBCDIC). A coded character set of 256 8-bit codes.
extended count key data (ECKD). An extension of
the CKD architecture.
Extended Remote Copy (XRC). A function of a
storage controller that assists a control program to
maintain a consistent copy of a logical volume on
another storage facility. All modifications of the primary
logical volume by any attached host are presented in
order to a single host. The host then makes these
modifications on the secondary logical volume.
F
fabric. In fibre-channel technology, a routing structure,
such as a switch, receives addressed information and
routes to the appropriate destination. A fabric can
consist of more than one switch. When multiple
fibre-channel switches are interconnected, they are said
to be cascaded .
failover. The routing of all transactions to a second
controller when the first controller fails. See cluster .
fast write. A write operation at cache speed that does
not require immediate transfer of data to a DDM. The
subsystem writes the data directly to cache, to
nonvolatile storage, or to both. The data is then
available for destaging. A fast-write operation reduces
the time an application must wait for the I/O operation to
complete.
FBA. See fixed-block address .
FC-AL. See Fibre Channel - Arbitrated Loop .
FCP. See fibre-channel protocol .
FCS. See fibre-channel standard .
Fibre Channel - Arbitrated Loop (FC-AL). An
implementation of the fibre-channel technology that
uses a ring topology for communication. In this topology
two or more fibre-channel end points are interconnected
through a looped interface. The ESS supports this
topology.
fibre-channel protocol (FCP). For fibre-channel
communication the protocol has five layers. The layers
define how fibre-channel ports interact through their
physical links to communicate with other ports.
fibre-channel standard (FCS). An ANSI standard for
a computer peripheral interface. The I/O interface
defines a protocol for communication over a serial
interface that configures attached units to a
communication fabric. The protocol has two layers. The
IP layer defines basic interconnection protocols. The
upper layer supports one or more logical protocols.
Refer to ANSI X3.230-199x.
FICON. Fibre-channel connection for mainframe
computers and peripherals that use ESCON
architecture, such as the IBM ES/9000 family.
field replaceable unit (FRU). An assembly that is
replaced in its entirety when any one of its components
fails. In some cases, a field replaceable unit may
contain other field replaceable units.
FIFO. See first-in-first-out .
firewall. A protection against unauthorized connection
to a computer or a data storage system. The protection
is usually in the form of software on a gateway server
that grants access to users that meet authorization
criteria.
first-in-first-out (FIFO). A queuing technique in which
the next item to be retrieved is the item that has been in
the queue for the longest time. (A)
fixed-block address (FBA). An architecture for logical
devices that specifies the format of and access
mechanisms for the logical data units on the device.
The logical data unit is a block. All blocks on the device
are the same size (fixed size). The subsystem can
access them independently.
FlashCopy. An optional feature for the ESS. With
FlashCopy you can make an instant copy of data, that
is, a point-in-time copy of a volume.
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Glossary
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