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service delivery transaction—A request or response sent through the service delivery subsystem.
signal—(n) A detectable asynchronous event possibly accompanied by descriptive data and parameters. (v)
The act of generating such an event.
single transition (ST)—The latching of data only on the assertion edge of the REQ or ACK signals.
source device—The SCSI device from which a service delivery transaction originates. See destination device.
SPI information unit—Data structures that encapsulate data, status, command, task attributes, iuCRC, and
nexus information into various formats.
SPI L_Q information unit—The SPI L_Q information unit (see Section 6.2.2, tables 49 and 50) contains L_Q
nexus (Logical unit—Q tag relationship) information for the information unit that follows, the type of information
unit that follows, and the length of information unit that follows. A SPI L_Q information unit shall precede all SPI
command information units, SPI multiple command information units, SPI data information units, SPI status
information units, and the first of an uninterrupted sequence of SPI data stream information units.
subsystem—An element in a hierarchically partitioned system which interacts directly only with elements in
the next higher division or the next lower division of that system.
suspended information—Information stored within a logical unit that is not available to any pending tasks.
target—A SCSI device which receives SCSI commands and directs such commands to one or more logical
units for execution.
task—An object within the logical unit representing the work associated with a command or group of linked
commands. A task consists of one initial connection and zero or more physical or logical reconnections, all per-
taining to the task.
task abort event—An event or condition indicating that the task has been aborted by means of a task man-
agement function.
task address—a SCSI initiator port identifies a task to a SCSI target port using a Task Address. The Task
Address object represents either a Tagged Task Address or an Untagged Task Address without regard for the
tagged or untagged nature of the Task. A Tagged Task Address is composed of a Logical Unit Identifier and a
Tag. An Untagged Task Address is composed of a Logical Unit Identifier.
task completion event—An event or condition indicating that the task has ended with a service response of
Task Complete.
task ended event—An event or condition indicating that the task has completed or aborted.
task management function—A task manager service which can be invoked by an application client to affect
the execution of one or more tasks.
task management request—A request submitted by an application client, invoking a task management func-
tion to be executed by a task manager.
task management response—The response returned to an application client by a task manager on comple-
tion of a task management request.
task manager—A server within the target which executes task management functions.
task set—A group of tasks within a SCSI target port device, whose interaction is dependent on the queuing
and auto contingent allegiance rules of Section 7.6.1.
task slot—Resources within the logical unit that may be used to contain a task.
task tags—A Tag is a field containing up to 64 bits that is a component of a Tagged Task Identifier. A SCSI ini-
tiator port assigns tag values in each Tagged Task Identifier in a way that ensures that the identifier uniqueness
requirements stated in ANSI SAM-4, T10/1683-D, are met.
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Parallel SCSI Interface Product Manual, Rev. A
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