Customization of the journal recovery count

 

This topic is about using the Journal Recovery Count (JRNRCYCNT) parameter in the CHGJRN command to set the journal recovery ratio for each journal.

This parameter will indicate how many journal entries can exist between the last deposited entry and the oldest forced entry for a journaled object. A value between 10 000 and 2 000 000 000 will be allowed. A value of *SYSDFT will also be allowed to reset the journal’s recovery count to the system default journal recovery count.

The journal recovery count allows you to choose between faster abnormal IPL recovery and decreased run time processing. Specifying a smaller value decreases the number of changes that would need to be recovered from this journal during an abnormal IPL by increasing the frequency with which changed objects are forced. Specifying a larger value increases the number of changes that would need to be recovered for this journal during an abnormal IPL by decreasing the frequency with which changed objects are forced.

Changing the journal recovery count value may affect overall system performance as it affects the utilization of auxiliary storage devices.

The WRKJRNA command indicates the Journal Recovery Count on the panel display and in the printed output. A value of *SYSDFT displays if the system default journal recovery count is being used. All journals are created with the system default journal recovery count, and if a value other than the system default (*SYSDFT) is specified, the system default journal recovery count will no longer be in effect for the journal. The Retrieve Journal Information API will also return the Journal Recovery Count.

The operating system is shipped with a system default journal recovery count of 250 000. The QJOCHRVC API changes the system default journal recovery count for all newly created journals on the system and all existing journals that have the system default (*SYSDFT) specified for their journal recovery count.

 

Parent topic:

Planning setup for journals