Reverting to previous versions

This section tells you what to do if you want to revert to using a previous version of WebSphere MQ for z/OS for some exceptional reason.

If you choose to revert to a previous version of WebSphere MQ, note that, as a general rule, data such as attributes (or in some cases, objects) relating to the new function in V6 will be lost. The more you have used the new functions of V6, the less practical it will be to go back to an earlier version.

If you want to revert to an earlier version of WebSphere MQ, contact your IBM support center. The support center will provide you with the 'Coexistence PTF', which apply to your system to revert to an earlier version. The information in the PTF includes a description of the data relating to new function that will be lost.

When you have reverted to a previous version, if you have defined a CF structure with CFLEVEL(4), that structure, queues defined to use it, and any messages on those queues are not accessible while running with a version of code earlier than V6.0. The queues and messages are retained, but if the Coupling Facility fails and all members of the queue-sharing group have been reverted to a previous level, messages might be lost. When you have reverted to V5.3.1, CF structures with a CFLEVEL less than 4, queues, and nonpersistent messages are still available.

WebSphere MQ V6.0 allows page sets up to 64GB but earlier versions allowed page sets only up to 4GB. If your page set 0 is larger than 4GB it is not possible to fall back to a previous release and restart the queue manager. If other page sets are found to be larger than 4GB when a queue manager restarts in an earlier MQ release, they will be taken off line and messages on them will not be available.

If you migrate from MQSeries V5.2 or earlier, consider carefully whether you will need the ability to revert to that release. We cannot revert to that release if you migrate directly to V6.0. If you think you will need to revert, migrate to V5.3.1 first and then migrate from V5.3.1 to V6.0. This allows you to revert first to V5.3.1 and then to your previous release.