Specifications

holding status for the channel, and the channel
responded with the stack-status control the last time the
control unit attempted to present the status.
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.
STI. See self-timed interface.
storage area network. A network that connects a
company’s heterogeneous storage resources.
storage complex. Multiple storage facilities.
storage device. A physical unit that provides a
mechanism to store data on a given medium such that it
can be subsequently retrieved. See disk drive module.
storage facility. (1) A physical unit that consists of a
storage server integrated with one or more storage
devices to provide storage capability to a host computer.
(2) A storage server and its attached storage devices.
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 are not provided by the storage
device. The storage server has one or more clusters.
striping. A technique that distributes data in bit, byte,
multi-byte, record, or block increments across multiple
disk drives.
subchannel. A logical function of a channel subsystem
associated with the management of a single device.
subsystem identifier (SSID). A number that uniquely
identifies a logical subsystem within a computer
installation.
support catcher. A server to which a machine sends
a trace or a dump package.
support catcher telephone number. The telephone
number that connects the support catcher server to the
ESS to receive a trace or dump package. See support
catcher. See remote technical assistance information
network.
switched fabric. One of three a fibre-channel
connection topologies supported by the ESS. See
arbitrated loop and point-to-point.
symmetric multi-processor (SMP). An
implementation of a multi-processor computer consisting
of several identical processors configured in a way that
any subset of the set of processors is capable of
continuing the operation of the computer. The ESS
contains four processors set up in SMP mode.
synchronous write. A write operation whose
completion is indicated after the data has been stored
on a storage device.
System/390. See S/390.
system adapter identification number (SAID).
System Management Interface Tool (SMIT). An
interface tool of the AIX operating system for installing,
maintaining, configuring, and diagnosing tasks.
System Modification Program (SMP). A program
used to install software and software changes on MVS
systems.
T
TAP. See Telocator Alphanumeric Protocol.
target. A SCSI device that acts as a slave to an
initiator and consists of a set of one or more logical
units, each with an assigned logical unit number (LUN).
The logical units on the target are typically I/O devices.
A SCSI target is analogous to an S/390 control unit. A
SCSI initiator is analogous to an S/390 channel. A SCSI
logical unit is analogous to an S/390 device. See Small
Computer System Interface.
TB. See terabyte.
TCP/IP. See Transmission Control Protocol/Internet
Protocol.
Telocator Alphanumeric Protocol (TAP). An industry
standard protocol for the input of paging requests.
terabyte (TB). (1) Nominally, 1 000 000 000 000
bytes, which is accurate when speaking of bandwidth
and disk storage capacity. (2) For ESS cache memory,
processor storage, real and virtual storage, a terabyte
refers to 2
40
or 1 099 511 627 776 bytes.
thousands of power-on hours (KPOH). A unit of time
used to measure the mean time between failures
(MTBF).
time sharing option (TSO). An operating system
option that provides interactive time sharing from remote
terminals.
TPF. See transaction processing facility.
track. A unit of storage on a CKD device that can be
formatted to contain a number of data records. See
home address, track-descriptor record, and data record.
track-descriptor record (R0). A special record on a
track that follows the home address. The control
program uses it to maintain certain information about
200 ESS Host Systems Attachment Guide
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