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special symbols with a coded character
set of 256 eight-bit codes.
extended count key data (ECKD)
An extension of the count key data (CKD)
architecture.
extent A continuous space on a disk that is
occupied by or reserved for a particular
data set, data space, or file. The unit of
increment is a track. See also multiple
allegiance and parallel access volumes.
extent pool
A groups of extents. See also extent.
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.
failback
Pertaining to a cluster recovery from
failover following repair. See also failover.
failover
Pertaining to the process of transferring all
control to a single cluster when the other
cluster in the storage unit fails. See also
cluster and failback.
fast write
A write operation at cache speed that
does not require immediate transfer of
data to a disk drive. 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 architecture.
FC See feature code. Note: FC is a common
abbreviation for fibre channel in the
industry, but the DS8000 customer
documentation library reserves FC for
feature code.
FC-AL See Fibre Channel-Arbitrated Loop.
FCP See fibre-channel protocol.
FCS See fibre-channel standard.
feature code (FC)
A code that identifies a particular
orderable option and that is used by
service personnel to process hardware
and software orders. Individual optional
features are each identified by a unique
feature code.
fibre channel
A data-transmission architecture based on
the ANSI Fibre Channel standard, which
supports full-duplex communication. The
DS8000 supports data transmission over
fiber-optic cable through its fibre-channel
adapters. See also fibre-channel protocol
and fibre-channel standard.
Fibre Channel-Arbitrated Loop (FC-AL)
An implementation of the Fibre Channel
standard that uses a ring topology for the
communication fabric. Refer to American
National Standards Institute (ANSI)
X3T11/93-275. In this topology, two or
more fibre-channel end points are
interconnected through a looped interface.
fibre-channel connection (FICON)
A fibre-channel communications protocol
designed for IBM mainframe computers
and peripherals.
fibre-channel protocol (FCP)
A protocol used in fibre-channel
communications with five layers that
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 (for example, FCP for
SCSI command protocols and SBCON for
zSeries command protocols). Refer to
American National Standards Institute
(ANSI) X3.230-199x. See also
fibre-channel protocol.
fibre-channel topology
An interconnection topology supported on
fibre-channel adapters. See also
point-to-point connection, switched fabric,
and arbitrated loop.
334 IBM TotalStorage DS8000: Messages Reference