Adding or deleting DEDB databases using online change

You can add or delete a DEDB database by using the online change function.

The following figure shows the overall process for adding a database using online change.

Figure 1. Adding a database using online change
begin figure description. This figure is described in the surrounding text. end figure description.

Adding or deleting a DEDB and implementing the change by means of the IMS online change facility requires that you perform the following steps.

Procedure

  1. MODBLKS level system definition (Stage 1 and Stage 2) to add or delete the DEDB. The changes for the IMS.MODBLKS data set should be generated into the active IMS system's staging copy of the IMS.MODBLKS data set, which is offline.
  2. DBDGEN, PSBGEN and ACBGEN to generate the application control blocks to add or delete the DEDB and PSBs that access it. The changed or new application control blocks must be generated into the active IMS system's staging copy of the IMS.ACBLIB data set, which is offline.
  3. Run the online change utility, DFSUOCU0, to move the changed IMS.MODBLKS data set and IMS.ACBLIB data set from the staging libraries to the inactive (A or B) copies of these libraries that are online to the active IMS system.
  4. Enter and follow the online change command sequence for PREPARE processing.
    If a DEDB is being added to an IMS system that does not have Fast Path installed, the DFS2833 error message will appear and the PREPARE process will be aborted.

    If a DEDB is added whose areas have CI sizes that exceed the system buffer size (BSIZ=), message DFS2832 appears and the PREPARE process aborts.

    Finally, if a DEDB is added to an IMS system that was initialized without any DEDBs, message DFS2837 appears and the PREPARE process aborts.

    Output threads are initialized during Fast Path initialization only if DEDBs are currently generated in the system. In order for the user to be able to add DEDBs with online change, IMS must be initialized with DEDBs to begin with.

  5. If the DEDB is to be deleted, any BMP region or DBCTL thread scheduled for access to the DEDB must first be stopped. Full function transactions scheduled for access to the DEDB will be placed in a QSTOP state and as a result, MPP or IFP dependent regions need not be stopped to implement the online change to delete the DEDB.
  6. If the DEDB is to be deleted, access to it from the active IMS system must be removed by means of a /DBR DB command. The commit will fail with a DFS3452 message if the DEDB has not had the /DBR command successfully run against it beforehand.
  7. Execute the online change command sequence for COMMIT/ABORT processing.
  8. If the DEDB is newly added, execute the following additional steps at any appropriate time prior to making the DEDB generally available for normal user access:
    1. Execute the normal procedures for defining the new DEDB and its areas and area data sets to DBRC and the RECON data sets.
    2. Define and initialize all of the area data sets belonging to the new DEDB.
    3. Execute the procedures to include the required Dynamic Allocation definitions that will enable the DEDB and its areas to be allocated to the active IMS system. Or register the DEDB and its areas to DBRC, and DBRC will dynamically allocate them during IMS initialization.
    4. Enter the /START DATABASE and /START AREA commands to make the DEDB and its areas accessible to the active IMS system.
    5. Run the necessary application load programs.