IBM MQ maintenance

Maintenance is the application of a reversible fix. Any changes to queue manager data are compatible with the previous code level.

Distributed[IBMi]Maintenance is the process of applying interim fixes or fix-packs.

[z/OS]Maintenance is the process of applying program temporary fixes on z/OS®.

An important characteristic of applying maintenance is that it must be reversible. Reversibility implies two things:

  1. The previous level of code is fully restored.
  2. Changes that are made to IBM® MQ objects are compatible. Changes are things like the creation or deletion of persistent messages, changes to queue managers, channels, topics, and queues. New and modified objects continue to work correctly with the restored level of code.

The reversibility of a maintenance package limits the extent of functional changes that are included in a maintenance package. No irreversible changes are included in a maintenance package. But, reversibility has limits. A maintenance package might include new programming and administrative interfaces. If you build new or modified applications to use the new interfaces, those applications do not work, if the maintenance package is removed.

Multi-instance queue managers are a good example. Should you remove the Version 7.0.1 fix pack that upgraded Version 7.0, then multi-instance queue manager functions no longer work. However, the queue managers continue to function correctly as single instance queue managers in Version 7.0.

On a smaller scale, a fix pack or interim fix might introduce a new configuration parameter to solve a problem. If you remove the fix pack or interim fix, although the new interface introduced by the change is not available any more, IBM MQ works with any objects that have been changed by the configuration parameter. For example, a new Java system property might introduce a parameter to set a code page for queue manager data conversion. The fix does not change any existing persistent queue manager state information. It can be removed, and the queue manager continues to work as before, but without the capability introduced in the fix.