Maintaining and migrating IBM MQ

Maintenance, upgrade, and migration have three distinct meanings for IBM® MQ. The definitions are described here. The following sections describe the various concepts associated with migration, followed by the various tasks needed; these tasks are platform-specific where needed.

About this task

Attention: The information in this section applies to both Continuous Delivery (CD) and Long Term Support (LTS) releases.

Any information that applies specifically to an LTS or CD release is marked with the appropriate icon.

IBM MQ uses the terms maintenance, upgrade and migration as follows:
Maintenance is the application of a fix pack, cumulative security update (CSU), interim fix or Program Temporary Fix (PTF).
Maintenance has one main characteristic. Those fixes, whether they are applied by using a maintenance installation tool, or installed by using a manufacturing refresh on top of an installation, are at the same command level as the existing code. No migration is required after applying maintenance. The installation can be restored to its previous level and any changed queue managers or applications will continue to work at the restored code level. However, you should test applications with the new level of IBM MQ code.
For more information, see Applying maintenance to IBM MQ.
Upgrading is the process of taking an existing IBM MQ installation and upgrading to a new level of code.
Unless you are upgrading the fix level of IBM MQ, but not its command level, an upgrade must be followed by migration. Upgrades can be backed out, as long as no migration has taken place. The process of removing an upgrade varies by platform and how the upgrade was applied. Upgrades that change the command level of IBM MQ require queue manager migration before applications can reconnect.
For more information, see Upgrading IBM MQ.
Migration is the process of updating queue manager data to match a newer level of code.
Migration occurs the first time a queue manager is started with the newer level of code, and always follows an upgrade that changes the queue manager command level, both automatic and manual changes. Migration is the transformation of queue manager data, applications, and the environment that the queue manager runs in. Once migration has occurred, the queue manager can no longer be started by an earlier code level. On most platforms, queue manager migration is not reversible:
  • [UNIX, Linux, Windows, IBM i]Migration cannot be reversed on IBM MQ for Multiplatforms. This restriction applies whether your enterprise uses the Long Term Support (LTS) release or Continuous Delivery (CD) release model.
  • [z/OS]IBM MQ for z/OS® queue managers can only be backwards migrated from an LTS release to an earlier LTS release. [MQ 9.2.0 Jul 2020]This statement also applies to those CD releases that have the same VRM as an LTS release, for example IBM MQ 9.2.0 CD. For more information, see IBM MQ release types.
For more information, see Migrating IBM MQ.