Queue manager migration

After upgrading an installation, queue manager migration might be required. Migration takes place when you start a queue manager. You can remove an upgrade before you have started a queue manager. However, if you remove the upgrade after a queue manager has been started, the queue manager will not work.

Migrating a queue manager to a later release

[z/OS] On IBM® MQ for z/OS®, queue manager migration is required after upgrading to a different version, release, or maintenance level of the product. The upgrade changes the command level. The current command, or VRM, level is shown in the z/OS console log.

[UNIX, Linux, Windows, IBM i] On IBM MQ for Multiplatforms, queue manager migration is always required for changes in the first two values of the VRMF, the V and the R. Changes in the maintenance and fix level, M and F in the VRMF, never cause automatic queue manager migration. A change in the command level always requires queue manager migration, but if the change is shipped in a maintenance or fix pack, you have the choice of whether to increase the command level, and cause queue manager migration.

Command level always increases with a change in version or release. If you decide to use new function introduced in a maintenance level upgrade, you must change the command level. The converse is not the case. You do not have to change the command level when the fix level changes. You can decide to install the fix pack, but not use the new function. Whether or not you use the new function, the installation of the fix pack increases the maximum command level supported by the installation. Run the dspmqver command to display the current maximum supported command level.

Queue manager migration is the process of converting persistent queue manager data from one version to another. Persistent queue manager data includes log files and data in the queue manager directory. The data records changes to objects such as messages, subscriptions, publications, queue managers, channels, queues, and topics.

Queue manager migration is required and largely automatic.

If an issue is encountered during migration of a queue manager or its objects, a warning message is generated detailing which object and attribute failed to migrate. Common reasons for this are:

A queue manager at an earlier version than IBM MQ 10.0 was migrated and the certificate label could not be converted to multi-certificate label version.

You can reduce the downtime and risk caused by queue manager migration, by verifying the new version first, using a different queue manager. Unless the platform supports queue manager coexistence, you need to perform the verification on a different server, or in a virtualized environment on the same server. If the platform you are upgrading supports queue manager coexistence, you can install the new version of IBM MQ on the same server, verify it, and minimize downtime to the time required to stop, backup, and restart the queue manager.

Note: If you are migrating a queue manager through multiple release levels, one level at a time, you must start the queue manager after each upgrade to migrate it. You must also start all the channels, to ensure they are migrated.

When migrating queue managers that are members of a cluster, migrate full repositories before partial repositories. This is because an older repository cannot store newer attributes introduced in a newer release. It tolerates them, but does not store them.

Restoring a queue manager to an earlier release

[UNIX, Linux, Windows, IBM i] For IBM MQ for Multiplatforms, you cannot restore a queue manager to an earlier release level after you have migrated it to a new release. You must back up your system before starting backwards migration. You can either back up queue manager data, or use a backup queue manager; see Backing up and restoring IBM MQ. Before backing up, you must stop the queue manager.

[z/OS] For IBM MQ for z/OS, an IBM MQ 10.0.0 LTS or IBM MQ 10.0.0 CD queue manager can always be backwards migrated to the release it was previously running at, if the release was one of IBM MQ 9.3.0 LTS, IBM MQ 9.3.0 CD, IBM MQ 9.4.0 LTS, or IBM MQ 9.4.0 CD.