Journaling Changed
Bytes Only

Hey, Ted:

I recall reading that when using commit control in V5R1 you can specify that only the changed fields be journaled. Can you point me in a direction where I can find the details behind this practice?

-- Gary

V5R1 has a new journaling parameter called Minimize entry-specific data (MINENTDTA), which gives you a way to record only changed bytes in files and data areas when journaling. Commitment control has nothing to do with it. You can specify MINENTDTA in the Create Journal (CRTJRN) and Change Journal (CHGJRN) commands.

Before you decide to use this feature, be aware of a few limitations.

First, the iSeries allows you to journal physical files, access paths, data areas, data queues in the QSYS.LIB file system and stream files, directories, and symbolic links in the Integrated File System (IFS), but MINENTDTA can only be used with physical files and data areas.

Second, the Compare Journal Images (CMPJRNIMG) command won't work with journals that record minimized entry-specific data.

Third, you cannot restore or replicate a journal containing minimized entry-specific data to an iSeries that is running a release prior to V5R1.

For more information, see page 409 of the V5R1 Backup and Recovery manual (SC41-5304-05), which is available on the Web in PDF format from the IBM Information Center, then click on the following links in the folders pane:

• Database and file systems
• DB2 UDB for iSeries
• Manuals and Redbooks
• Backup and Recovery

Thanks to Larry Youngren and Jeff Tenner of IBM for their help in answering this question.

-- Ted