Migration steps for an existing IMS catalog in systems that use ACB libraries

Like other IMS databases, the IMS catalog is defined by a DBD and accessed through PSBs. The migration procedure for the IMS catalog differs depending on which version of IMS you migrate from, and if you are migrating multiple IMS systems that share the catalog. If you are migrating from IMS Version 13, the ACBs for the catalog must be generated from the DBDs and PSBs that IMS 15.5 supports. If you are migrating from IMS 14, you do not need to re-generate the catalog ACBs. Additionally, when the ACBs for the other databases and program views in the IMS system are re-generated for the new IMS release, the IMS catalog must be updated with those ACBs to keep the IMS catalog in sync with the active ACBs in use by the IMS system.

Ensure that enough storage is allocated to the IMS catalog to accommodate the insertion of a complete IMS 15.5 set of the existing DBD and PSB resources.When migrating from IMS Version 13, the IMS catalog holds a complete set of your existing resources and a complete set of IMS 15.5 resources.

Updating an IMS catalog for a new release can take a long time. Before you populate the IMS catalog, consider tuning your buffer pools based on the number and types of segments in the IMS catalog so that the utility you use for population doesn't do many buffer steals.

If you are migrating from IMS Version 13, you must generate the catalog ACBs from the DBDs and PSBs that IMS 15.5 supports by using the IMS 15.5 ACB Generation and Catalog Populate utility (DFS3UACB). The DBDs and PSBs for the catalog changed between IMS Version 13 and IMS 15.5. Step 3 is required.

If you are migrating from IMS 14, you do not need to generate new catalog ACBs from the DBDs and PSBs. The DBDs and PSBs for the catalog did not change between IMS 14 and IMS 15.5. Skip step 3.

The following steps update an existing IMS catalog for a new version of IMS.

Attention: Do not delete and rebuild the IMS catalog if the IMS catalog contains metadata that cannot be restored from the new version of the ACB library. Metadata that cannot be restored from the ACB library includes metadata that is required for database versioning, remarks, or metadata stored by non-IMS products.

Procedure

  1. If necessary, increase the amount of storage that is allocated to the IMS catalog.
  2. Shut down IMS 15.5 if it is running.
  3. If you are migrating from IMS Version 13, install the IMS 15.5 DBDs and PSBs for the IMS catalog from the IMS.SDFSRESL data set to the IMS.DBDLIB and IMS.PSBLIB data sets. You do not need to unload and reload the IMS catalog database, even though the IMS catalog DBD might have changed in the new release.
    The catalog DBDs are called DFSCD000 and DFSCX000. The PSBs are called DFSCPL00, DFSCP000, DFSCP001, DFSCP002, and DFSCP003. These are reserved names and cannot be changed or used for other resources.

    If the IMS catalog is shared by multiple systems and you are migrating from IMS Version 13, you must create a temporary DBDLIB that you will install the IMS 14 DBDs into. This DBDLIB is used to hold the IMS 14 catalog DBDs until migration is complete.

    If you are migrating from IMS Version 13 and you assigned an alias to the IMS Version 13 catalog, run the IMS Catalog Alias Names utility (DFS3ALI0) after you install the IMS 15.5 catalog DBDs from the IMS.SDFSRESL data set to the IMS.DBDLIB. You must run the DFS3ALI0 utility after you install the IMS 15.5 catalog DBDs to the IMS.DBDLIB so that the IMS catalog alias references the IMS 15.5 catalog DBD instead of the IMS Version 13 catalog DBD.

  4. Use the IMS 15.5 ACB Generation and Populate utility (DFS3UACB) to generate the ACBs for all your application PSBs and database DBDs and add them to the IMS catalog.
    The DFS3UACB utility generates the ACBs and updates the IMS catalog in a single job step, ensuring that the IMS catalog is in sync with the latest ACBs.

    As an alternative to using the ACB Generation and Catalog Populate utility (DFS3UACB), you can run both the IMS 15.5 ACB Maintenance utility and the IMS Catalog Populate utility. The ACB Maintenance utility builds the ACBs. The IMS Catalog Populate utility populates the IMS catalog with the new versions of PSBs and DBDs.

  5. Activate the ACB library.
  6. Restart the IMS 15.5 system.

If you have any application programs that read the IMS catalog, review the structure of the IMS catalog to ensure that the application programs can handle any changes appropriately.

After testing is complete and you are certain that you do not need to fall back to the previous version of IMS, you can remove the DBD and PSB resource instances for the past IMS version from the IMS catalog by using the IMS Catalog Record Purge utility (DFS3PU10).