IBM TOTAL STORAGE DS8000 User Manual
Page 354
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
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Reference