Migration Challenges

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I covered the planning steps necessary to migrate to DB2 UDB for z/OS Version 8 in a previous article (see “DB2 Universal Database for z/OS Version 8: Pre-Planning Your Migration,” in the April/May 2004 issue of z/Journal).

IBM documents the V8 migration process in the DB2 V8 Installation Guide, and provides additional information and planning tips on its Website. We won’t go into the specifics and prerequisites of the migration in this article; instead, we’ll concentrate on the major steps (or “modes”) of DB2 during the migration and the typical issues IT shops face at each point.

Issues Prior to Migration

Before running any DB2 V8 migration jobs, you must begin with a DB2 Universal Database (UDB) for z/OS and OS/390 V7 subsystem. Here, you must make several decisions regarding your software maintenance strategy.

Your software maintenance strategy determines how soon and when you’ll apply maintenance to your suite of mainframe software (DB2, CICS, z/OS, IMS, DFSMS, JES, and so forth). There’s an excellent IBM manual describing how to develop a strategy titled Parallel Sysplex: Software Management for Availability, SG24-5451. This will help you determine how often to apply preventive maintenance (PTFs), HIPERs, ServerPacs, and so forth.

Another aspect of software maintenance is whether you’ll take advantage of Recommended Service Upgrade (RSU) or Consolidated Service Test (CST). For more information on CST and RSU, visit the IBM Website mentioned at the end of this article.

At some point prior to migration, you must upgrade the DB2 ERLY code; this may require an Initial Program Load (IPL). See my previously mentioned article for more details.

Migration Steps and Typical Issues

Figure 1 shows the V7-to-V8 migration process. This process chart doesn’t show the actual or recommended elapsed times to spend in each mode. Many shops intend to stay in Compatibility Mode (CM) for several weeks to several months. After that, running the Enable New Function Mode (ENFM) job may take an hour or more, after which they migrate directly to New Function Mode (NFM) and run comfortably. Your experiences may vary.

Compatibility Mode

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