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protocol service request—A call to the lower level protocol service layer to begin a protocol service transac-
tion.
protocol service response—A reply from the upper level protocol layer in response to a protocol service indi-
cation.
quick arbitration and selection process (QAS)—Quicker than the normal arbitration and selection process.
Implementation is optional for SCSI devices.
queue—The arrangement of tasks within a task set, usually according to the temporal order in which they were
created. See task set.
queue tag—The parameter associated with a task that uniquely identifies it from other tagged tasks for a logi-
cal unit from the same initiator.
receiver—A client or server that is the recipient of a service delivery transaction.
reference model—A standard model used to specify system requirements in an implementation-independent
manner.
request—A transaction invoking a service.
request-response transaction—An interaction between a pair of distributed, cooperating objects, consisting
of a request for service submitted to an object followed by a response conveying the result.
request-confirmation transaction—An interaction between a pair of cooperating objects, consisting of a
request for service submitted to an object followed by a response for the object confirming request completion.
reset event—A protocol-specific event which may trigger a hard reset response from a SCSI device as
described in Section 5.3.
response—A transaction conveying the result of a request.
SCSI application layer (SAL)—The protocols and procedures that implement or invoke SCSI commands and
task management functions by using services provided by a SCSI protocol layer.
SCSI device—A device that contains at least one SCSI port and the means to connect its drivers and receiv-
ers to the bus.
SCSI device identifier—An address by which a SCSI device is referenced within a domain.
SCSI I/O system—An I/O system, consisting of two or more SCSI devices, a SCSI interconnect and a SCSI
protocol, which collectively interact to perform SCSI I/O operations.
SCSI protocol layer—The protocol and services used by a SCSI application layer to transport data represent-
ing a SCSI application protocol transaction.
sender—A client or server that originates a service delivery transaction.
server—A SCSI object that performs a service on behalf of a client.
service—Any operation or function performed by a SCSI object, which can be invoked by other SCSI objects.
service delivery failure—Any non-recoverable error causing the corruption or loss of one or more service
delivery transactions while in transit.
service delivery port—A device-resident interface used by the application client, device server or task man-
ager to enter and retrieve requests and responses from the service delivery subsystem. Synonymous with
"port."
service delivery subsystem—That part of a SCSI I/O system which transmits service requests to a logical
unit or target and returns logical unit or target responses to a SCSI initiator port.
Parallel SCSI Interface Product Manual, Rev. A
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