Upgrade, migration, and maintenance of IBM MQ on z/OS

You can install new releases of IBM® MQ to upgrade IBM MQ to a new maintenance, release, or version level. Multiple installations at the same or different levels can coexist on the same z/OS® instance. Running a queue manager at a higher level requires migration. Maintenance differs from upgrading. To maintain a level of IBM MQ, you apply Program Temporary Fixes (PTFs) to the installed code.

Applying PTFs does not change the version, release, or maintenance level of the code. No queue manager migration is required after applying maintenance. PTFs are grouped into Recommended Service Updates (RSUs) that have been tested together in a Consolidated Service Test (CST); see Consolidated Service Test and the RSU.

When you install a new VRM level of IBM MQ on z/OS using SMP/E, it creates a set of IBM MQ libraries. The libraries for different VRM levels of IBM MQ can coexist on the same instance of z/OS. You can then run different queue managers against different release levels of IBM MQ on the same z/OS instance.

If you start a queue manager running on a later release level, then migration of the queue manager to that release level is required. Even if the difference is only in the modification level, some migration might be required. The migration tasks you must perform to migrate from one version to another are documented in z/OS: Migration planning to the latest release; see also Changes that affect migration.

From Version 7.0.1, after you have fully migrated a queue manager to a new version or release, reverse migration is not possible. Before Version 7.0.1, full migration took place when you started a queue manager for the first time at the new release level. For Version 7.0.1 and later versions, you have control over when migration takes place, using a new CSQ6SYSP parameter, OPMODE ; see z/OS: OPMODE. If your queue manager is on Version 7.0 or earlier, you can revert to an earlier release. You might have to contact your IBM support center for a backward migration PTF.

Using OPMODE, you can migrate all your existing applications to the new release level, and still be able to revert to the previous release level. Once you start changing applications, or adding applications that use new function, you cannot revert to the previous level of IBM MQ. OPMODE applies to migration from Version 6.0 to Version 7.0.1, onwards.

OPMODE gives you the option of enforcing a two-stage migration process:
  1. Regression test your existing applications.
  2. Develop new applications, and change existing applications, to use the new function in the release.
The strategy for upgrading queue managers at Version 6.0 or later is as follows:
  1. Apply the coexistence and backward migration PTFs to all the queue managers you are going to upgrade. After applying the PTFs, you can run queue managers of different levels in the same queue sharing groups. You can also reverse the migration of a queue manager back to your current level.
  2. Upgrade the first queue manager.
  3. Check all your existing applications run correctly on this queue manager.
  4. Bring all the queue managers in a queue sharing group up to the new level, and check that existing applications continue to work correctly.
  5. Change the setting of OPMODE so that applications can use new function on all the queue managers in the queue sharing group.
    Note: Step 5 is the point of no return. You can no longer run that queue manager at the previous level of IBM MQ.
  6. To enable new IBM MQ v7.1, or later, function, restart all queue managers within the queue sharing group.
The coexistence and backward migration PTFs have two distinct purposes: 1
  1. To allow queue managers at the earlier release level to coexist with ones at the later release level. In particular for queue managers to coexist in the same queue sharing group.
  2. To handle queue manager data and logs formatted using the data definitions of the later release.

On z/OS, maintenance is supplied as Program Temporary Fixes, PTFs, which are applied and removed using SMP/E. PTFs are specific to a particular set of libraries corresponding to specific release level. Apart from any exceptions documented with the PTFs, PTFs do not change the correct operation of IBM MQ. Nonetheless, you must check that the fixes have not changed the operation of critical programs unexpectedly.

PTFs that apply to a category of software fixes might be grouped together and identified using a fix category. For further information, see IBM Fix category values and descriptions.

Characteristics of different types of upgrade on z/OS

When you upgrade from one release to another, or apply maintenance in the form of PTFs, on z/OS, the impact of the change depends on the extent of the change in VRM level. The VRM codes are explained in The version naming scheme for IBM MQ for z/OS.

PTF upgrades do not require migration, and are reversible. From Version 7.0.1, all upgrades from Version 6.0 or later are reversible if the OPMODE has not been set to NEWFUNC.

1 Coexistence and backward migration changes might be shipped as a single or multiple fixes.