Reverting a queue manager to a previous release on z/OS
After migrating to IBM MQ for z/OS® Version 9.0.0 Long Term Support (LTS) release, from either Version 7.1.0 or Version 8.0.0, we can backward migrate, or fallback, to the version you were using prior to migration. Backward migration Program Temporary Fixes (PTFs) are available for both Version 7.1.0 and Version 8.0.0. Backwards migration is not supported for a Continuous Delivery (CD) release.
Before you begin
In general, after fallback to IBM WebSphere MQ Version 7.1, new attributes of IBM MQ objects introduced at Version 9.0 will be removed. The APAR that supplies these PTFs, documents specific information relating to fallback to IBM WebSphere MQ Version 7.1 or to IBM MQ Version 8.0.0.
Switching back to running a queue manager with the target libraries of a previous version is possible if DISPLAY SYSTEM returns COMPAT,vrm,nnn where vrm is the level of the previous version.
- 7 or 8
- is the version number v of the product.
- r
- is the release number of the product.
- m
- is the modification number of the product.
If it does, we can go back to using your customization and startup procedure for the queue manager from that version:
- The queue manager compatibility level must be 710 or 800. This
will be the case if the queue manager has never been started with OPMODE set to
(NEWFUNC,900).
- DISPLAY SYSTEM returns OPMODE COMPAT,710,nnn or OPMODE COMPAT,800,nnn.
- Before migrating your queue manager to the latest version, with that version of target libraries, you applied all the migration and toleration PTFs to the queue manager on your previous version. The queue manager then started successfully with those PTFs at that previous version. This is a requirement before we can revert your queue manager to the original version.
- You saved the queue manager customization macros and JCL for running with the Version 7.1 or Version 8.0
target libraries.
- We can re-create the customization for Version 7.1 or Version 8.0 , if the originals are not available to you.
To restart the queue manager, so that it runs at the version where it was migrated from, just requires that you switch back to using the libraries for the previous version.
Note that it is not necessary to roll back the early code for this installation when reverting your queue manager to an earlier version.
Procedure
- Stop the listener, channel initiator, and queue manager.
-
Switch back to use the MSTR and CHINIT started procedure JCLs with Version 7.x or Version 8.0
libraries.
In case data set aliases are used for load libraries, switch the aliases to refer to the Version 7.x or Version 8.0 libraries.
For example, an alias named MQM.MQP1.SCSLOAD, referring to MQM.MQV800.SCSLOAD, needs to change to refer to MQM.MQV7xx.SCSLOAD.
-
Restart the queue manager, using the system parameter module (CSQZPARM) used with IBM WebSphere MQ Version 7.x, or IBM MQ Version 8.0, prior to migration, and linking to the Version 7.x, or Version 8.0,
code.
- Until we have verified the startup, start the queue manager, channel initiator, and listener separately, checking for errors on the console after each component is started. If the startup runs cleanly, combine the startup of all three components in the production environment.
- Start the queue manager.
- Start the channel initiator.
- Start the listener.
- Verify correct functioning of existing applications.
Results
If the queue manager cannot be reverted to the previous release by following the preceding procedure, for example, because it has been started with OPMODE set to (NEWFUNC,900), the queue manager can only be reverted to the previous release by recovering the page sets, BSDSs, and active logs from back up copies taken before the migration to IBM MQ for z/OS Version 9.0.
All updates made since the back up was taken will be lost. See How to back up and recover pagesets for more information on backing up IBM MQ resources.