DB2 & IMS

Many IT organizations are planning their move to DB2 10 because the benefits are quite compelling. While DB2 10 has features that can benefit most customers, all customers are interested in the reduction of CPU this version delivers. The reduction can be substantial (some organizations have seen up to 20 percent) and will enable users to run more business transactions without having to upgrade their systems. Other enhancements include increased availability, concurrency, reduced catalog contention, virtual storage relief, and temporal data. These new features are available in different DB2 10 modes; this means that for some of the features you will get the benefits in Conversion Mode (the new name for Compatibility Mode). For other features, you will have to wait until the switch to New Function Mode. Depending on the complexity of your DB2 environment, this could mean you’re a year or more away from being able to use some of the DB2 10 features.

As you plan for your DB2 10 migration, there are hundreds of items to consider. Here are some you should include in your list:

1. Document your reasons for moving to this release. Whether your need to move to DB2 10 is application-driven, performance-driven, or a combination of both, making the move will involve a considerable investment of time, hardware resources, and other costs. The business justification for the migration should be documented. A justification that’s unique to DB2 10 is the CPU savings, which can translate to a substantial cost savings based on your company’s annual costs per MIPS. This migration could result in lower monthly license charges for DB2 and z/OS if you pay by variable workload license charges.

2. Benchmark performance of your previous version of DB2. One of the primary reasons for moving to DB2 10 may be to obtain the CPU savings. Be sure to capture current DB2 CPU resource consumption to prove to management that the investment of time, hardware resources, and other costs justify the migration.

3. Consider multi-mode migration. A DB2 10 migration involves progressing through multiple migration modes. Move first to Conversion Mode, followed by Enable New Function Mode, and finally to New Function Mode. IBM is enabling a migration from DB2 Version 8 directly to DB2 10. This will eliminate the need for a future migration and its associated costs (from DB2 9 to DB2 10). You will also benefit from the CPU savings in DB2 10 over DB2 9. But don’t wait too long to start your migration; IBM drops support for DB2 V8 on April 30, 2012.

4. Beware of access path changes that can hurt performance. Any DBA who has migrated from one version of DB2 to another has experienced performance degradation as a result of access path changes. For DB2 10, IBM states that most of the performance improvements can be achieved by migrating to DB2 10 and rebinding the plans. The documentation states that the performance improvement can be twice as great as without rebinding the plans. IBM also provided new keywords that will attempt to keep the same access path, but there are limitations on the use of the new keywords, such as when the package was created (DB2 9 or later).

To adequately test the impact of DB2 10 on existing plans, you will need to explain the SQL statements on a DB2 10 subsystem with object statistics matching your production environment. Ideally, you should create a baseline from your current DB2 version by EXPLAINING both static and dynamic SQL statements from your production workload, and then comparing the access paths with those from the EXPLAINS run on DB2 10. There are tools available to help with this exercise.

5. Coordinate your DB2 management product migration with your DB2 system migration. Check with your DB2 management products provider to determine what version of its management products supports DB2 10. One version of the DB2 management product may support both your current DB2 version (8 or 9) and DB2 10. Depending on which DB2 management products you have installed, this could dramatically reduce the time and effort required to perform the migration testing. This may require you to migrate to the latest version of your DB2 management tools before migrating to DB2 10, with a payback of dramatically reducing the time and effort to migrate to DB2 10.

Cost Savings With DB2 10

While the migration to DB2 10 requires some necessary planning and presents technical challenges, the overall cost savings can prove significant. It may be well worth the investment of both time and expenditures for the IT organization interested in enhanced system, hardware, and database management.