Seagate Ultra160 Product Manual page 25

SCSI Interface Product Manual, Rev. B 7
peer entities—Entities within the same (protocol) layer.
pending task—A task that is not a current task.
physical interconnect—A single physical pathway for the transfer of information between SCSI devices in a
domain.
physical reconnect—The act of resuming a nexus to continue a task. A SCSI target port initiates a physical
reconnect when conditions are appropriate for the physical bus to transfer data associated with a nexus
between a SCSI initiator port and a SCSI target port.
physical reconnection—The result of a physical reconnect that exists from the assertion of the BSY signal in
a SELECTION or RESELECTION PHASE. A physical reconnection ends with the BUS FREE PHASE (see
Section 3.1.1) or a QAS REQUEST message (see Section 4.3.13).
port—Synonymous with "service delivery port." A single attachment to a SCSI bus from a SCSI device.
procedure—An operation that can be invoked through an external calling interface.
protocol—The rules governing the content and exchange of information passed between distributed objects
through the service delivery subsystem.
protocol option—An option whose definition within a SCSI protocol standard is discretionary.
protocol service confirmation—A signal from the lower level protocol service layer notifying the upper layer
that a protocol service request has completed.
protocol service indication—A signal from the lower level protocol service layer notifying the upper level that
a protocol transaction has occurred.
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—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.