Seagate SCSI Interface Product Manual page 18

4 SCSI Interface Product Manual, Rev. J
confirmation—A response returned to an object, which signals the completion of a service request.
confirmed protocol service—A service available at the protocol service interface, which requires confirma-
tion of completion.
current task—A task that is in the process of sending messages, sending status, transferring data, or transfer-
ring command data to or from the initiator.
cyclic redundancy check (CRC)—An error detecting code used to detect the validity of data that has been
transferred during the current data phase.
destination device—The SCSI device to which a service delivery transaction is addressed. See source
device.
device server—An object within the logical unit which executes SCSI tasks according to the rules for task
management described in clause 7 of ANSI SAM-2 document, T10/1157D.
device service request—A request, submitted by an application client, conveying a SCSI command to a
device server.
device service response—The response returned to an application client by a device server on completion of
a SCSI command.
differential—A signalling alternative that employs differential drivers and receivers to improve signal-to-noise
ratios and increase maximum cable lengths.
disconnect—The action that occurs when a SCSI device releases control of the SCSI bus, allowing it to go to
the Bus Free phase.
domain—An I/O system consisting of a set of SCSI devices that interact with one another by means of a ser-
vice delivery subsystem.
dormant (task state)—The state of a task that is prevented from starting execution due to the presence of cer-
tain other tasks in the task set.
double transition (DT)—The latching of data on both the assertion edge and the negated edge of the REQ
(ACK) signal.
driver—The circuitry used to control the state of the bus.
enabled (task state)—The state of a task that may complete at any time. Alternatively, the state of a task that
is waiting to receive the next command in a series of linked commands.
ended command—A command that has completed or aborted.
exception condition—Any event that causes a SCSI device to enter an auto contingent allegiance or contin-
gent allegiance condition.
faulted initiator—The initiator to which a Command Terminated or Check Condition status was returned.
faulted task set—A task set that contained a faulting task.
faulting command—A command that completed with a status of Check Condition or Command Terminated.
faulting task—A task that has completed with a status of Check Condition or Command Terminated.
function complete—A logical unit response indicating that a task management function has finished. The
actual events comprising this response are protocol specific.
hard reset—A target response to a reset event or a Target Reset in which the target performs the operations
described in Section 4.6.6.
implementation—The physical realization of an object.
implementation-specific—A requirement or feature that is defined in a SCSI-3 standard but whose imple-
mentation may be specified by the system integrator or vendor.
implementation option—An option whose actualization within an implementation is at the discretion of the
implementor.