IBM DS8000 User Manual page 237

not require modifications to the host
software in order to continue to provide
an existing function.
source device
One of the devices in a dual-copy or
remote-copy volume pair. All channel
commands to the logical volume are
directed to the source device. The data on
the source device is duplicated on the
target device. See also target device.
spare A disk drive on the DS8000 that can
replace a failed disk drive. A spare can be
predesignated to allow automatic
dynamic sparing. Any data preexisting on
a disk drive that is invoked as a spare is
destroyed by the dynamic sparing copy
process.
spatial reuse
A feature of serial storage architecture
that enables a device adapter loop to
support many simultaneous read/write
operations. See also serial storage
architecture.
SSID See subsystem identifier.
SSR See service support representative.
stacked status
For System z, the condition when the
control unit is in a holding status for the
channel, and the last time the control unit
attempted to present the status, the
channel responded with the stack-status
control.
stage operation
The operation of reading data from the
physical disk drive into the cache.
staging
To move data from an offline or
low-priority device back to an online or
higher priority device, usually on demand
of the system or on request of the user.
standard volume
A volume that emulates one of several
System z volume types, including 3390-2,
3390-3, 3390-9, 3390-2 (3380-track mode),
or 3390-3 (3380-track mode), by
presenting the same number of cylinders
and capacity to the host as provided by
the native System z volume type of the
same name.
STI See self-timed interface.
storage area network
A network that connects a company's
heterogeneous storage resources.
storage capacity
The amount of data that a storage
medium can hold; usually expressed in
kilobytes, megabytes, or gigabytes.
storage complex
A configuration of one or more storage
units that is managed by a management
console.
storage device
A physical unit that provides a
mechanism to store data on a given
medium such that it can be subsequently
retrieved. See also disk drive module.
storage extent
The minimum contiguous range of
storage on a physical storage device,
array, or rank that can be allocated to a
local volume
storage image
A partitioning of a storage unit that
provides emulation of a storage server
with one or more storage devices that
provides storage capability to a host
computer. You can configure more than
one storage image on a storage unit.
(DS8000 series only)
storage server
A physical unit that manages attached
storage devices and provides an interface
between them and a host computer by
providing the function of one or more
logical subsystems. The storage server can
provide functions that the storage device
does not provide. The storage server has
one or more clusters.
storage unit
A physical unit that consists of a storage
server that is integrated with one or more
storage devices that provide storage
capability to a host computer.
storage unit identifier
A unique identifier for a storage unit that
consists of a manufacturer, a model
number, a type number, a plant of
manufacture, and a sequence number.
striping
A technique that distributes data in bit,
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Glossary