SCSI Primary Commands - 2.pdf

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T10/1236-D Revision 20 18 July 2001If the SERVICE ACTION RESERVATION KEY field is not associated with a reservation the device server shall perform apreempt by doing the following in an uninterrupted series of actions:a) remove the registration for the initiator or initiators identified by the SERVICE ACTION RESERVATION KEY fieldspecified in the PERSISTENT RESERVE OUT parameter list;b) ignore the contents of the SCOPE and TYPE fields;c) process tasks as defined in 5.5.1; andd) establish a unit attention condition for any other initiator that lost its registration. The sense key shall be setto UNIT ATTENTION and the additional sense data shall be set to REGISTRATIONS PREEMPTED.If a PERSISTENT RESERVE OUT specifying a PREEMPT service action sets the SERVICE ACTION RESERVATIONKEY field to a value that does not match any registered reservation key the device server shall return a RESER-VATION CONFLICT status.5.5.3.6.4 Preempting an existing persistent reservation with the PREEMPT AND ABORT service actionThe initiator’s request for and the device server’s responses to a PERSISTENT RESERVE OUT commandPREEMPT AND ABORT service action are identical to the PREEMPT service action (see 5.5.3.6.3) except for thefollowing additions. If no reservation conflict occurred, the device server shall perform the following uninterruptedseries of actions:a) Perform the uninterrupted series of actions described for the PREEMPT service action (see 5.5.3.6.3);b) All tasks from preempted initiators (called preempted tasks) shall be terminated and initiator notificationshall be provided as specified by the TAS bit in the Control mode page (see 8.3.6) that applies to thepreempted initiator as follows:A) If the TAS bit is set to zero then all preempted tasks shall be terminated as if an ABORT TASK SET taskmanagement function had been performed by each preempted initiator; orB) If the TAS bit is set to one then all preempted tasks from initiators other than the initiator that sent thePREEMPT AND ABORT service action shall be terminated with a TASK ABORTED status (seeSAM-2). The preempted tasks from the initiator that sent the PREEMPT AND ABORT service action (ifany) shall be terminated as if an ABORT TASK SET task management function had been performed bythat initiator.If a terminated task is a command that causes the device server to generate additional commands anddata transfers (e.g., EXTENDED COPY), all commands and data transfers generated by the commandshall be terminated before the ABORT TASK SET task management function is considered completed.After the ABORT TASK SET function has completed, all new tasks are subject to the persistent reservationrestrictions established by the preempting initiator;c) The device server shall clear any ACA or CA condition associated with an initiator being preempted andshall clear any tasks with an ACA attribute from that initiator. If the TST field is 000b (see 8.3.6) and ACA orCA conditions exist for initiators other than the initiator being preempted, the PERSISTENT RESERVEOUT command shall be terminated prior to processing with a status of ACA ACTIVE if the NACA bit equalsone (see SAM-2) or BUSY if the NACA equals zero. If the TST field contains 001b, then ACA or CA conditionsfor initiators other than the initiator being preempted shall not prevent the execution of thePERSISTENT RESERVE OUT command; andd) For SCSI devices that implement the PREVENT ALLOW MEDIUM REMOVAL command, the device servershall perform an action equivalent to the execution of a PREVENT ALLOW MEDIUM REMOVAL commandwith the PREVENT field equal to zero for the initiator or initiators being preempted (see 7.12).The actions described in the preceding list shall be performed for all initiators that are registered with the SERVICEACTION RESERVATION KEY value, without regard for whether the preempted initiator(s) hold the reservation.Any asynchronous event reporting operations in progress are not affected by the PREEMPT AND ABORT serviceaction.36 dpANS SCSI Primary Commands - 2 (SPC-2)
18 July 2001 T10/1236-D Revision 205.5.3.6.5 Clearing a persistent reservationAny application client may release a persistent reservation and remove all registrations from a device server for aspecific logical unit by issuing a PERSISTENT RESERVE OUT command with a service action of CLEAR serviceaction through a registered initiator with the following parameter:a) RESERVATION KEY set to the value of the initiator/logical unit pair’s established reservation key.In response to this request the device server shall perform a clear by doing the following as part of an uninterruptedseries of actions:a) Release any persistent reservation associated with the logical unit;b) Remove all registration(s) (see 5.5.3.4);c) Ignore the contents of the SCOPE and TYPE fields;d) continue normal execution of any tasks from any initiator that have been accepted by the device server asnonconflicting; ande) establish a unit attention condition for all other registered initiators, if any, for the cleared logical unit. Thesense key shall be set to UNIT ATTENTION and the additional sense data shall be set to RESERVATIONSPREEMPTED.Application clients should not use the CLEAR service action except during recoveries that are associated withinitiator or system reconfiguration, since the effect of the CLEAR service action is to remove the persistent reservationmanagement conventions that protect data integrity.5.6 Multiple port and multiple initiator behaviorSAM-2 specifies the behavior of logical units being accessed by more than one initiator. Additional service deliveryports provide alternate service delivery paths through which the device server may be reached and may alsoprovide connectivity for additional initiators. An alternate path may be used to improve the availability of devices inthe presence of certain types of failures and to improve the performance of devices whose other paths may bebusy.If a SCSI device has more than one service delivery port, the arbitration and connection management among theservice delivery ports is vendor specific. If one service delivery port is being used by an initiator, accessesattempted through other service delivery port(s) may:a) receive a status of BUSY; orb) be accepted as if the other service delivery port(s) were not in use.The device server shall indicate the presence of multiple ports by setting the MULTIP bit to 1 in its standardINQUIRY data.For the purposes of handling reservations, other initiators are defined as all initiators on the same service deliveryport except the initiator holding the reservation and all initiators on all other service delivery ports. Only thefollowing operations allow an initiator to interact with the tasks of another initiator, regardless of the service deliveryport:a) the PERSISTENT RESERVE OUT with PREEMPT service action preempts persistent reservations forother initiators (see 5.5.3.6.3);b) the PERSISTENT RESERVE OUT with PREEMPT AND ABORT service action preempts persistent reservationsand all tasks for other initiators (see 5.5.3.6.4);dpANS SCSI Primary Commands - 2 (SPC-2) 37
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