Seagate Ultra160 Product Manual page 23

SCSI Interface Product Manual, Rev. B 5
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 SCSI target port response to a reset event or a SCSI target port Reset in which the target per-
forms the operations described in Section 7.6.7.
implementation—The physical realization of an object.
implementation-specific—A requirement or feature that is defined in a SCSI standard but whose implemen-
tation 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.
indication—The second step in a four-step confirmed service reply to a request.
information unit transfer—Parallel transfers that transfer data, status, commands, task attributes, task man-
agement information, acrid, and nexus information using only SPI information units.
initial connection—The result of a physical connect. It exists from the assertion of the BSY signal in a
SELECTION PHASE until the next BUS FREE PHASE or the next QAS REQUEST message.
initiator—A SCSI device containing application clients which originate device service and task management
requests to be processed by a SCSI target port SCSI device.
interconnect—The electrical media (including connectors and passive loads) used to connect the TERM-
PWR, terminators, and SCSI devices in a SCSI bus.
interconnect subsystem—One or more physical interconnects which appear as a single path for the transfer
of information between SCSI devices in a domain.
intersymbol interference (ISI)—The effect of adjacent symbols on the symbol currently being received.
in transit—Information that has been sent to a remote object but not yet received.
I/O operation—An operation defined by an unlinked SCSI command, a series of linked SCSI commands or a
task management function.
I/O process—An I/O process consists of one initial connection or, if information units are enabled, the
establishment of a nexus, and a zero or more physical or logical reconnection all pertaining to a single task or
a group of tasks. An I/O process begins with the establishment of a nexus. If the SPI information unit transfers
are disabled, an I/O process normally ends with a Command Complete message. If information unit transfers
are enabled, an I/O process ends with a SPI L_Q information unit with the type field set to status and the Data
Length field set to zero.
I T nexus—A nexus that exists between a SCSI initiator port and a SCSI target port.
I T L nexus—A nexus that exists between a SCSI initiator port, a SCSI target port, and a logical unit. This rela-
tionship replaces the prior I T nexus.
I T L Q nexus—A nexus between a SCSI initiator port, a SCSI target port, a logical unit, and a queue tag fol-
lowing the successful receipt of one of the queue tag messages. This relationship replaces the prior I T L
nexus.