Termination phase of the XRF process
While a takeover is a termination in the sense that it removes the active IMS from service, termination as a separate XRF phase occurs when an operator stops one or both of the IMS systems.
The termination phase, shown in the following figure, returns the XRF complex to two separate and independent environments and stops all activity in the alternate IMS.
The three types of termination of the active IMS are:
- Normal Shutdown
- In a normal shutdown (/CHECKPOINT FREEZE) of the XRF complex, IMS checkpoint processing occurs. When this has completed, IMS writes a X'06' log record and the alternate IMS terminates automatically. The active IMS tells AVM that processing is terminating with I/O prevention.
- Planned Takeover
- A SWITCH SYSTEM command is entered on the active IMS, a quiesce of dependent region processing is done on the active IMS, and a X'06' log record is written indicating that the alternate subsystem is to take over processing. The active IMS communicates to AVM that a normal takeover is occurring.
- Abnormal Termination
- In an abnormal termination of the active subsystem, an attempt is made to purge the log buffer and write a X'06' log record. The active IMS terminates from AVM abnormally.
The two types of termination of the alternate IMS are:
- Normal Shutdown
- The operator can stop the alternate IMS by entering /STOP BACKUP on the alternate IMS or /CHECKPOINT FREEZE or /CHECKPOINT DUMPQ on the active IMS. In both cases, the alternate IMS leaves AVM and specifies I/O prevention.
- Abnormal Termination
- The IMS ESTAE exit is entered and the alternate subsystem terminates abnormally from AVM.