Eliminate the manual BACKMIG command requirement for compatibility with older MQ versions.

Starting with MQ 9.3, IBM introduced the BACKMIG command to convert MQ datasets to a format compatible with older versions (MQ backout). Without using BACKMIG, the Queue Manager may encounter issues when starting on a lower version. Therefore, it is necessary to issue the BACKMIG command when planning to start the MQ Queue Manager with a lower MQ version.

As we plan to upgrade to a new MQ version, there is a possibility that we may need to back out the MQ version if any issues arise. As part of the backout process, we issue the BACKMIG command when all other tasks are down, repoint the MQ libraries to the lower MQ version, and perform an IPL to start MQ with the lower version.

For every MQ backout, the MQ team needs to back out all other dependent tasks, unmanage every MSTR, issue the BACKMIG command, and then manage automation. For QSG Queue Managers, we also need to start the corresponding DB2 before issuing BACKMIG and stop the same DB2 after issuing BACKMIG. If there are additional mandatory tasks for the MQ upgrade as part of the new MQ migration, this will require involvement from multiple teams across all environments.

Altogether, this increases the time required due to dependencies and the need to issue the BACKMIG command for each queue manager on every sysplex, compared to previous MQ backout migrations. Therefore, we need assistance in obtaining the old backout method or, at the very least, in removing the need to manually issue the BACKMIG command to convert MQ datasets to a format compatible with older versions.