Restarting the IMS subsystem without using RECON data sets

When the IMS DEDB Fast Recovery job completes, you must restart the IMS subsystem.

About this task

The steps in this topic guide you through the process of recovering DEDBs when the RECON data set cannot be used.

The entire recovery procedure is explained in three separate topics. The steps in this topic describe the second task, from the completion of an IMS DEDB Fast Recovery job to the next IMS cold start.

The following diagram depicts the flow of the recovery procedure from the completion of an IMS DEDB Fast Recovery job to the next IMS cold start.

1. Recover the DBRC RECON data set.

   Perform the following substeps to recover the DBRC RECON data set and to maintain database integrity during the IMS cold start:

   1. Initialize the RECON data set by using DBRC INIT commands such as INIT.RECON, INIT.DB, INIT.DBDS, INIT.ADS, INIT.IC, INIT.CAGRP, and INIT.CA.
   2. Register all available DEDB area data sets with the DBRC CHANGE command.

      All area data sets are made unavailable after performing Step 1.a. The DEDB Area Status list contains only those areas that were open at the time of IMS failure. Collect information from the latest DBRC LIST.RECON command output list and the console log to register those area data sets whose areas were not opened.

   3. Register the following database and database data set status by using the DBRC CHANGE command:
      • RECOVERY NEEDED
      • PROHIBIT FURTHER AUTHORIZATION
      • READ ONLY

      After performing Step 1.a, the status of all DEDB areas is changed to RECOVERY NEEDED.

   Tip: To be prepared to recover the RECON data set at any time, execute the DBRC LIST.RECON command and generate the RECON data set list daily.
2. Archive all OLDSs that are not archived.

   After the processing of Step 1, the contents of the RECON data set are initialized and, therefore, the OLDSs that have not been archived might be reused. Therefore, you must copy all OLDSs that are not archived to SLDS by using the Log Archive utility. When you use this utility, you must prepare your own JCL because the DBRC GENJCL.ARCHIVE command cannot be used. The Log Archive utility must be executed without using the DBRC function (DBRC=N on the EXEC parameter).

3. Determine whether any databases or areas need to be recovered.

   Whether a database or an area needs to be recovered is indicated by the status codes in the Database Status list and in the DEDB Area Status list. If the status code shows RCVNEED for a resource, the resource requires recovery.

   When one or more resources have the RCVNEED status code, run the Database Recovery utility. The Database Recovery utility must be executed without using the DBRC function (DBRC=N on the EXEC parameter) because it is difficult to recover the online log records and image copy data set information in the DBRC RECON data set.

4. Determine whether the database backout is needed by referring to the Backout Required PSB list.

   If database backout is needed, run the Batch Backout utility.

5. Run the MSDB Dump Recovery utility.

   If the last-used OLDS has been already closed by the Log Recovery utility before the IMS DEDB Fast Recovery execution, the MSDB Dump Recovery utility and IMS DEDB Fast Recovery can be executed concurrently.

6. Perform a cold start on the IMS subsystem by entering the /ERE COLDSYS command.