Altering shared HALDB databases when ACB libraries are used

When ACB libraries are used, all of the IMS systems that participate in the alter operation read the database changes from members in the staging ACB library.

The staging ACB library can be shared or each of the IMS systems can have its own staging ACB library. However, if the staging ACB library is not shared, the ACB members that are used by each IMS system must be copies that are created by the same execution of the ACB Maintenance utility.

When the alter operation begins, all of the IMS systems in the IMSplex issue message DFS3197I to acknowledge the start of alter processing, even if the IMS systems do not access the database that is being altered.

During the alter operation, no IMS system can initiate either another alter operation of the database that is being altered or a HALDB online reorganization of the database that is being altered.

Each IMS system issues message DFS3198I when it stops altering the partitions that it started. In a data sharing environment, IMS systems can issue one of two versions of DFS3198I: DFS3198I HALDB ALTER ENDED... or DFS3198I HALDB ALTER COMPLETED.... An IMS system issues DFS3198I HALDB ALTER ENDED... if either alter processing was interrupted or one or more of the partitions in the HALDB database were altered by another IMS system. The other IMS systems might or might not have finished altering the partitions that they started. An IMS system issues DFS3198I HALDB ALTER COMPLETED... if it altered all of the partitions in the HALDB database itself and alter processing is complete for all of the partitions in the database.

Use member online change to activate the ACB members in the staging ACB library for all of the IMS systems that share the database.

If you use either global or local online change, after alter processing is complete and before online change is performed, the ACB members that contain the database changes must be copied into the inactive ACB library that is used by each IMS system.