Using DBRC

This topics explains how to use DBRC with partitioned databases and partitioned indexes.

Partitioned Databases

DBRC keeps track of the state of each data set in regards to image copy, recovery and EEQEs. A counter of the number of DBDSs that need recovery, image copy or have EEQEs are also kept for the whole database.

DBRC DB and DBDS Flags/Counters

In this example, the registered database has just been loaded or reorganized. All data sets require image copy. The database has a counter of 3 because 3 DBDSs have image copy needed flags turned on.

Database authorization for update programs cannot be done until image copies are done for all data sets, which will turn off the image copy needed flag in the DBDSs and set the image copy counter in the DB to zero.

The is also true if recovery was needed for a data set and the data set does not have any EEQEs. Database authorization will fail if any DBDSs have recovery needed without any EEQEs, which results in a non-zero recovery needed counter for the database.

DBRC keeps track of DEDB AREAS independently. Image copy or recovery needed flags in an area do not inhibit authorization for the database.

Partitions are registered in DBRC as TYPE=IMS, which requires all data sets in the database to be available before authorizing the database. As mentioned earlier, counters are kept in the database that must be zero; otherwise, authorization fails. There are also flags in the database that indicate backout failed, which will also prevent authorization.

The whole database must be off-line during image copy and/or recovery because no subsystem can be authorized for the database when image copy or recovery are needed, unless the access requested by the subsystem is compatible, e.g. read only when image copy is needed.

Concurrent Image Copy (CIC)

The CIC option allows the Image Copy utility to use DBRC database sharing (SHARELEVEL=1|2|3) to image copy a partition while the data set is allocated for update to a subsystem. The use of CIC is recommended for on-line image copy of partitioned databases that are registered with DBRC.

CIC essentially replaces On-line Image Copy (OLIC) for ESDS and OSAM data sets.

CIC doesn’ t support on-line image copy of KSDS data sets, however.

Recovery

DBRC authorization prevents multiple data sets from being recovered at the same time for both multiple data set groups and partitions. You must recover to a non-registered data set to be able to recovery multiple partitions at the same time if the database is registered with DBRC.

Partitioned Indexes

When you use the IMS HISAM Reload utility to load a partitioned index, the image copy needed flag is set for the first index partition only.

It is recommended to register partitioned indexes as non-recoverable, so image copies will not be required. If you register the index as recoverable, you must ensure image copies of all partitions are taken after loading a partitioned secondary index.