Synchronization point processing and physical logging

Some 'clustering' of output and release of updated CIs and buffers occurs because DEDB updates are deferred until after physical logging is complete.

In BMPs, it helps to minimize the number of updates performed in any one sync interval, particularly if the program is to be run concurrent with the main bulk of message processing.

It is likely that, for performance reasons, the physical log record will be large, so that the log record might not be written for some time during low logging activity. However, IMS varies the interval between the periodic invoking of physical logging. This interval is directly related to the total logging activity in the IMS system. (Low activity causes a smaller interval to be set.)

The physical logging process can be relatively slow because of small physical log buffers or channel or control unit contention for the WADS/OLDS data sets.

The Fast Path environment can have high transaction rates and logging activity. Therefore, the physical configuration supporting the logging process must also be analyzed and altered for optimum performance.