User Manual

SCSI Commands Reference Manual, Rev. J 399
www.seagate.com Parameters for direct access devices
NUAR bit
1 A no unit attention on release (NUAR) bit set to one specifies that the device server shall not establish a unit attention condition as
described in 5.13.11.2.2.
0 A NUAR bit set to zero specifies that the device server shall establish a unit attention condition as described in SPC-5.
QERR (queue error management) field
The queue error management (QERR) field (see table 380) specifies how the device server shall handle other tasks when one task is terminated
with CHECK CONDITION status (see SAM-5). The task set type (see the TST field definition in this subclause) defines which other tasks are
affected. If the TST field equals 000b, then all tasks from all I_T nexuses are affected. If the TST field equals 001b, then only tasks from the same
I_T nexus as the task that is terminated with CHECK CONDITION status are affected.
DQUE (Disable Queuing) bit
NOTE The DQUE bit has been declared obsolete by the T10 committee and is not supported.
VS bit
0 The VENDOR SPECIFIC (VS) bit is not supported in Seagate products.
RAC (report a check) bit
1 The report a check (RAC) bit provides control of reporting long busy conditions or CHECK CONDITION status. A RAC bit set to one speci-
fies that the device server should return CHECK CONDITION status rather than returning BUSY status if the reason for returning the BUSY
status may persist for a longer time than that specified by the AUTOLOAD MODE field.
0 A RAC bit set to zero specifies that the device server may return BUSY status regardless of the length of time the reason for returning
BUSY status may persist.
UA_INTLCK_CTRL (unit attention interlocks control) field
The unit attention interlocks control (UA_INTLCK_CTRL) field (see table 381) controls the clearing of unit attention conditions reported in the
same I_T_L_Q nexus transaction as a CHECK CONDITION status and whether returning a status of BUSY, TASK SET FULL or RESERVATION CON-
FLICT results in the establishment of a unit attention condition (see SAM-5).
Table 380 Queue error management (QERR) field
Code Definition
00b
If an ACA condition is established, the affected tasks in the task set shall resume after the ACA condition is cleared
(see SAM-5). Otherwise, all tasks other than the task that received the CHECK CONDITION status shall be pro
-
cessed as if no error occurred.
01b
All the affected tasks in the task set shall be aborted when the CHECK CONDITION status is sent. If the TAS bit is set
to zero, a unit attention condition (see SAM-5) shall be established for the initiator port associated with every I_T
nexus that had tasks aborted except for the I_T nexus on which the CHECK CONDITION status was returned, with
the additional sense code set to COMMANDS CLEARED BY ANOTHER INITIATOR. If the TAS bit is set to one, all
affected tasks in the task set for I_T nexuses other than the I_T nexus for which the CHECK CONDITION status was
sent shall be completed with a TASK ABORTED status and no unit attention shall be established. For the I_T nexus
to which the CHECK CONDITION status is sent, no status shall be sent for the tasks that are aborted.
10b
Reserved
11b
Affected tasks in the task set belonging to the I_T nexus on which a CHECK CONDITION status is returned shall be
aborted when the status is sent.