Replication Guide and Reference

Operating in your replication environment

After your replication environment is up and running, and updates are replicated, you need to perform periodic maintenance tasks. These include the following tasks:

Configuring the pruning of control tables

The UOW and CD tables will grow too large if the contents are not pruned regularly. You can configure your system to prune automatically, or you can prune manually. You control how frequently obsolete information will be removed from these tables. If the tables aren't pruned often enough, the table space that they're in will run out of space, which will force the Capture program to stop. If they are pruned too often or during peak times, the pruning interferes with the change capture process. You can use the optimal pruning frequency for your replication environment.

Monitoring important criteria

There are many factors that determine how well your replication environment performs. You can use the Replication Monitor, which is part of DJRA, to generate a report that will help you monitor the activities of the Capture and Apply components, as well as the status of the subscription sets. For example, the report contains historical information to help you determine trends about subscription latencies.

Dealing with data modification conflicts

If you are using update-anywhere replication, and you did not design your configuration to prevent update conflicts, you must handle update conflicts and rejected transactions.

Performing regular database maintenance

If you want your replication environment to run smoothly, you must regularly perform database maintenance tasks. For example, use the RUNSTATS utility against the DB2 catalog tables to collect new statistics for tables and indexes. Also use the RUNSTATS utility once after the CD and UOW tables have sufficient data in them so that the DB2 Optimizer will use indexes on them. Periodically use the REORG utility (or the RGZPFM command in AS/400) for the change data tables, the unit-of-work table, and the target tables. You must also delete rows from the Apply trail table, which contains subscription set statistics and error information.

Coordinating with DB2 utility operations

If you want to run DB2 utilities (such as REORG, RUNSTATS, BIND PACKAGE, and REVOKE) that will use the table spaces that contain the replication control tables, you must stop the Capture and Apply programs before running the utilities.

Changing your replication configuration as your business needs change

You are likely to need to modify your replication environment from time to time. Whether you add a new column to an existing source table, or drop a source table, you will need to modify your replication criteria. Also, you will need to maintain password files.

Troubleshooting

If you find that your replication environment is not performing as you expected, or if you can't replicate data, you can run the Replication Analyzer. The Replication Analyzer is a tool that is shipped as a sample. You can use the Replication Analyzer to analyze the behavior of the Capture program or the Apply program. It can answer such questions as: "why is the Capture program not capturing?" and "why is the Apply program not applying?" The Replication Analyzer can help diagnose problems, verify replication setup, and offer suggestions for performance tuning. You can also look in the Apply trail table for status information about the Apply program, or in the Capture trace table for status information about the Capture program.

For general information about operating in a replication environment, see Operating DB2 DataPropagator. For information about operating in a particular operating system, see the appropriate chapter in Operations.

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