Queue manager migration
After upgrading an installation, queue manager migration might be required. Migration takes place when you start a queue manager.
![[z/OS]](ngzos.gif)
On z/OS®, queue manager migration is required after upgrading to a different version, release, or maintenance level. The upgrade changes the command level. The current command, or VRM, level is shown in the z/OS console log.
On other platforms, queue manager migration is always required for changes in the first two digits of the VRMF code. Changes in the maintenance and fix level, M and F in the VRMF code, never cause automatic queue manager migration. No migration was required for the upgrade from Version 7.0 to Version 7.0.1. The change from Version 7.0 to Version 7.0.1 did change the command level from 700 to 701. From Version 7.1 onwards, 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. On z/OS, you must migrate queue managers manually between compatability mode and new function mode by setting the OPMODE parameter.
After migrating to a new release , or on z/OS, after setting the OPMODE to NEWFUNC, the queue manager cannot be restored to an earlier release level.
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.