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consistency group interval time
The value in seconds that indicates the
length of time between the formation of
consistency groups.
consistent copy
A copy of a data entity (a logical volume,
for example) that contains the contents of
the entire data entity at a single instant in
time.
console
A user interface to a server, for example,
the interface provided on a personal
computer. See also IBM TotalStorage
Management Console.
contingent allegiance
For zSeries, a relationship that is created
in a control unit between a device and a
channel when the channel accepts
unit-check status. The allegiance causes
the control unit to guarantee access; the
control unit does not present the busy
status to the device. The allegiance
enables the channel to retrieve sense data
that is associated with the unit-check
status on the channel path associated with
the allegiance.
control path
The route that is established from the
master storage unit to the subordinate
storage unit when more than one storage
unit participates in a Global Mirror
session. If there is only one storage unit
(the master) in the Global Mirror session,
no control path is required.
control unit (CU)
1) A device that coordinates and controls
the operation of one or more input/output
devices, and synchronizes the operation
of such devices with the operation of the
system as a whole.
2) For zSeries, a storage server with
ESCON or OEMI interfaces. The control
unit adapts a native device interface to an
I/O interface that a zSeries host system
supports.
3) The portion of the storage unit that
supports the attachment of emulated
count key data devices over ESCON,
FICON, or OEMI interfaces. See also
cluster.
control-unit image
For zSeries, a logical subsystem that is
accessed through an ESCON I/O
interface. One or more control-unit images
exist in each control unit. Each image
appears as an independent control unit,
but all control-unit images share a
common set of hardware facilities. The
DS8000 can emulate 3990-3, TPF,
3990-6, or 2105 control units.
control-unit-initiated reconfiguration (CUIR)
A software mechanism that the DS8000
uses to request that an operating system
of a zSeries host verify that one or more
subsystem resources can be taken offline
for service. The DS8000 can use this
process to automatically vary channel
paths offline and online to facilitate bay
service or concurrent code installation.
Depending on the operating system,
support for this process might be model
dependent, might depend on the IBM
TotalStorage Enterprise Storage Server
Subsystem Device Driver, or might not
exist.
Coordinated Universal Time (UTC)
The international standard of time that is
kept by atomic clocks around the world.
Copy Services
A collection of optional software features,
with a Web-browser interface, used for
configuring, managing, and monitoring
data-copy functions.
Copy Services CLI
See Copy Services command-line
interface.
Copy Services client
Software that runs on each DS8000
cluster in the Copy Services server group
and that performs the following functions:
v Communicates configuration, status and
connectivity information to the Copy
Services server
v Performs data-copy functions on behalf
of the Copy Services server
Copy Services command-line interface (Copy
Services CLI)
The command-line interface software that
is provided with DS8000 Copy Services
and used for invoking Copy Services
functions from host systems attached to
the DS8000. See also command-line
interface.
Glossary 329