Migrating a non-DRD-enabled IMS system to DRD and an RDDS

To enable dynamic resource definition (DRD) with an resource definition data set (RDDS), you need to enable DRD, specify and allocate the RDDS, and import the resource definitions from the MODBLKS data set to the RDDS.

Recommendation: When migrating to DRD, use the IMSRSC repository instead of an RDDS, because the repository function is the strategic direction for IMS.

If resources need to be changed during migration, perform a MODBLKS online change operation on the IMS systems that have not migrated to DRD, and issue CREATE, UPDATE, and DELETE commands as necessary on the IMS systems that have migrated to DRD.

To enable DRD with an RDDS:

Procedure

  1. Shut down IMS normally.
  2. Define the following DRD parameters in the <DYNAMIC_RESOURCES> section of the DFSDFxxx member of the IMS.PROCLIB data set:
    • RDDSDSN=(dsname_1, dsname_n)

      These system definition data sets are for the resource definitions.

    • AUTOIMPORT=AUTO, which specifies that IMS automatically imports resource definitions. When AUTOIMPORT=AUTO, IMS checks the RDDS first. If the RDDS is empty, IMS loads the resource definitions from the IMS.MODBLKS data set. If the RDDS contains any resource definitions, IMS ignores any definitions in the IMS.MODBLKS data set.
      Note: If AUTOIMPORT=MODBLKS is specified, instead of AUTOIMPORT=AUTO, your runtime definitions are imported from the IMS.MODBLKS data set during IMS cold start. Any changes you make to your online system will not be recovered across the cold start. You can either perform another system definition that includes the changes you made online, or hereafter start IMS with AUTOIMPORT=AUTO specified in the DFSDFxxx PROCLIB member.
    • AUTOEXPORT=AUTO, which specifies that IMS automatically exports resource definitions to the RDDS data sets, the IMSRSC repository, or both, during system checkpoints.
  3. Enable DRD by specifying MODBLKS=DYN in either or both of the following locations:
    • The DFSCGxxx member of the IMS.PROCLIB data set
    • The <DYNAMIC_RESOURCES> section of the DFSDFxxx member of the IMS.PROCLIB data set
  4. Allocate the system RDDS data sets that are specified on the RDDSDSN= parameter in the DFSDFxxx member.
  5. Specify the IMS EXEC parameters DFSDF=xxx and, if MODBLKS=DYN was specified in the DFSCGxxx member, CSLG=xxx. These parameters identify which DFSDFxxx and DFSCGxxx members to use in the IMS.PROCLIB data set.
  6. Cold start IMS. If the RDDS data sets are empty, during cold start IMS imports the resource definitions in the IMS.MODBLKS data set to create the runtime resource definitions. The online change process for the IMS.MODBLKS data set is now disabled.
  7. Start using DRD to add (CREATE command), change (UPDATE command), or delete (DELETE command) the runtime resource definitions.
  8. At system checkpoint time, IMS automatically exports the definitions to the RDDS if any changes have been made. To export any changes immediately after they have been made, either issue a /CHE command, or issue an /EXPORT command.
  9. For subsequent cold starts of this IMS, specify AUTOIMPORT=RDDS in the <DYNAMIC_RESOURCES> section of the DFSDFxxx member of the IMS.PROCLIB data set. When AUTOIMPORT=RDDS is specified, IMS automatically imports resource and descriptor definitions from the RDDS during cold start processing.