SCSI Description
5-8 Maxtor Atlas 10K III
Under SCSI-2 processing, the Extended Contingent Allegiance condition extends
Contingent Allegiance handling so the initiator has explicit control over the point at
which suspended (queued) commands are resumed. It allows the initiator to send a
REQUEST SENSE command and then send the non-tagged commands to access the
drive’s medium.
This action is provided to fix damage left by the failed command before permitting the
drive to continue with processing the queued commands.
The Extended Contingent Allegiance condition is enabled and disabled b y the EECA
bit in the MODE SELECT Control Mo de page. The Extended Allegiance Condit ion
differs from the Contingent Allegiance in that, under the Extended Contingent
Allegiance condition:
•The drive sends an INITIATE RECOVERY message to the allegiance
initiator prior to returning the failed command’s COMMAND
C OM PLET E m es sage. If th e initi ato r re jects the IN IT IA T E
RECOVER Y message, the drive drops back to contingent allegiance
level of operation for the current error.
•An ABORT message does not terminate the extended contingent
allegian ce co ndition.
•Non-tagged drive acces s commands from the “allegianced” initiator are
accepted by the drive and take priority over all queued commands.
QUEU E FULL status is returned if the host sends a tagged command.
•The drive delays resuming or aborting the queued commands until a
RELE A SE RECOVE RY message is received from the initiator.
The extended contingent allegiance condition remains in effect until cleared by one
of the fol lowi ng :
•H ard re s et
•BUS D EVICE RE SET messag e from any initiator
•RELEASE RECOVERY message from the “allegianced” initiator