IBM® suggests that multiple JES2 members in the same sysplex use the AUTOEMEM option. The AUTOEMEM option makes jobs eligible for restart if another JES2 member (MVS™ and JES2) in a sysplex has failed.

The AUTOEMEM option has no effect on the DASD hardware lock. If it is held by a failed member, the operator must reset the lock.

The AUTOEMEM option has no effect on the Coupling facility lock, because that lock is released automatically when the JES2 address space ends.

If only the JES2 member fails, the operator must restart the JES2 member so that it can provide services for the jobs that continue to execute on the active MVS system.

As shown in Figure 1 and Figure 3, JES2 uses the cross-system coupling facility (XCF) to communicate status among JES2 members in a sysplex. When a participating MVS system fails, other JES2 members are notified through XCF. When a JES2 member fails, other JES2 members are notified through XCF. For information about XCF and the sysplex, see z/OS MVS Setting Up a Sysplex.

Figure 1 shows a sequence of events in a 2-member MAS configuration where the checkpoint resides on DASD, the software checkpoint lock is held by the failed JES2 member (SYSA), and the AUTOEMEM option is enabled. In this instance, only the JES2 member has failed; the MVS system (SYSTEMA) continues to process jobs. Note that the $HASP784 message appears in the SYSLOG only.

Figure 1. Sysplex with the AUTOEMEM option enabled, a JES2 failure (DASD)

On SYSTEMA:                         On SYSTEMB:

  JES2 Fails

                                    $HASP264 WAITING FOR RELEASE
                                            OF CKPT LOCK BY SYSA

                                    $HASP784 ATTEMPTING AUTOMATIC RESET
                                            OF JES2 MEMBER SYSA
                                   (JES2 automatically resets checkpoint lock)
Restart JES2

Figure 2 shows a sequence of events in a 2-member MAS configuration where the checkpoint resides on a Coupling facility structure, the Coupling facility lock that JES2 uses to control access to the checkpoint is held by the failed JES2 member (SYSA), and the AUTOEMEM option is enabled. In this instance, only the JES2 member has failed; the MVS system (SYSTEMA) continues to process jobs. The Coupling facility lock is released from SYSA and passed to the next waiting member of the queue. Note that the $HASP784 message appears in the SYSLOG only.

Figure 2. Sysplex with the AUTOEMEM option enabled, a JES2 failure (Coupling facilities)

On SYSTEMA:                       On SYSTEMB:

  JES2 Fails


                                  $HASP784 ATTEMPTING AUTOMATIC RESET
                                          OF JES2 MEMBER SYSA
                                 (JES2 automatically resets checkpoint lock)
Restart JES2

Figure 3 shows a sequence of events in a 2-member MAS configuration where the hardware lock and the software checkpoint lock are held by the failed JES2 member (SYSA), the MVS system (SYSTEMA) has failed, and the AUTOEMEM option is enabled. Note that the $HASP784 message appears in the SYSLOG only.

Figure 3. Sysplex with the AUTOEMEM option enabled, an MVS system failure

On SYSTEMA:                         
 On SYSTEMB:

  SYSTEMA Fails
  (For example, the
  system failed
  and entered
  a nonrestartable
  wait state.)

                                           $HASP263 WAITING FOR ACCESS
                                                     TO JES2 CHECKPOINT VOLUME...

SYSTEM RESET
 (Operator)
                                           $HASP264 WAITING FOR RELEASE
                                                     OF CKPT LOCK BY SYSA

                                           IXC402D SYSTEMA LAST OPERATIVE
                                                     AT hh:mm:ss ...
                                                     REPLY DOWN IF MVS IS DOWN ...

                                           R nn,DOWN 

                                           $HASP784 ATTEMPTING AUTOMATIC RESET
                                                     OF JES2 MEMBER SYSA
                                          (JES2 automatically resets checkpoint lock)

                                           $HASP493 SYSB MEMBER SYSA RESTART IS
                                                    IN PROGRESS
                                                    (JES2 automatically makes jobs
                                                    eligible for restart)

                                           $HASP492 SYSB MEMBER SYSA RESTART
                                                    HAS COMPLETED
Re-IPL SYSTEMA