Input to the Database Change Accumulation utility

In addition to using archived log data (SLDS and RLDS) as input to the Database Change Accumulation utility, you can also use a subset of the IMS log or a previous change accumulation data set. The utility writes the accumulated changes to a new change accumulation data set.

If the log data is on tape, you can specify all log volumes or a subset of log volumes as input to the Database Change Accumulation utility. When you specify a subset of log volumes, DBRC checks whether the subset is complete for each DBDS. A subset of log volumes is complete for a DBDS when all of the following conditions are true:

• The first volume in the subset is the volume with the first change to the DBDS since any of the following events occurred:
  • The last change accumulation.
  • The last image copy.
  • DBRC created the ALLOC record for this area (if the image copy was concurrent).
  • Checkpoint IDs that are found on logs prior to the run time of the image copy are included to ensure all updates are considered if the image copy was taken while updates were being made.
• The remaining volumes are in sequence.
• In a data-sharing environment, all logs containing changes for a DBDS are included.

Use the DBRC GENJCL.CA command to specify the subset of log volumes. You can request a specific number of log volumes either by volume (use the VOLNUM keyword) or by time stamp (use the CATIME keyword).

You can use a change accumulation data set as input to a later run of the Database Change Accumulation utility whether your subset of log volumes is complete or incomplete; however, you can use a change accumulation data set as input to the Database Recovery utility only if it represents a complete log subset.