Repairing the RECON data sets

You can fix specific problems that can occur in the RECON data sets to ensure data integrity.

Specific problems can arise in the RECON data sets that are often created outside the control of DBRC. In most cases, the problems are related to the DMB Table record and inconsistencies in the DMB number in the RECON header, database, and Fast Path area records. You can use the REPAIR.RECON command to rebuild or build the DMB Table record and fix inconsistent DMB numbers in the records.

The REPAIR.RECON command with the DMBTABLE keyword processes the entire DMB Table and all of the records that contain DMB numbers that are used to build or rebuild the DMB Table record. Use the command to make the following repairs:
  • Correct inconsistent DMB numbers, which involves ensuring the following items:
    • The high-order bit in the RECON header, database, and Fast Path area records is on
    • The DMB numbers in the partition database records match the DMB numbers in the HALDB master records
    • The DMB numbers in the Fast Path area records match the DMB numbers in the DEDB records
  • Update the number of registered databases in the RECON listing
  • Rebuild the DMB Table record or build the DMB Table record if it does not exist
The REPAIR.RECON command with the DMBNUM keyword also finds and corrects inconsistent DMB numbers, but allows the scope to be limited to all database records, specific types of database records (HALDB, Fast Path, or IMS), a specific database record, or the RECON header.
  • The ALL keyword causes all the database records to processed and ensures that the high-order bit is on in the in RECON header, database, and Fast Path area records, the DMB numbers in the partition database records match the DMB numbers in the HALDB master records, and the DMB numbers in the Fast Path area records match the DMB numbers in the DEDB records.
  • If the RESET keyword is specified with the RECON keyword, the DMB# and LAST USED# fields are set to 32767 if the DMB Table record exists. When the next database is registered in the RECON data set and these fields are set to 32767, the search in the DMB Table record for the next available DMB number to assign starts at 1 instead of from the last DMB number added.
  • The CHECK keyword determines whether any inconsistencies with the DMB numbers exist without fixing them. The UPDATE keyword both finds and correct errors with the DMB numbers.

DBRC can change the records to fix inconsistencies in the DMB numbers only if the database or area is unauthorized. When the command is processed, a message is issued for any database or area that is authorized. Unauthorize the identified databases or areas and then rerun the command.

Recommendations:
  • The REPAIR.RECON command has the potential of impacting the availability of the RECON data set because of the number of records that might be read and changed. First, run REPAIR.RECON command on a backup copy of the RECON data set to assess the impact. Then, run the command when access to the actual RECON data set is minimal. For REPAIR.RECON DMBNUM, run the command first with the CHECK keyword on the backup copy, and, if any DMB numbers need to be fixed, then run the command with the UPDATE keyword on the actual RECON.
  • Schedule the REPAIR.RECON DMBNUM CHECKUP to run at least once a year to ensure the integrity of your RECON data sets and run the command before upgrading the RECON. If errors are found, rerun the command with the UPDATE keyword to fix the errors.