Changing the maximum OSAM data set size for a HALDB from 8 GB to 4 GB

Use the CHANGE.DB command to decrease the maximum size of OSAM PHDAM and PHIDAM data sets for a HALDB database.

When you reduce the data capacity of the OSAM data sets from 8 GB to 4 GB, you must consider how to manage the data in the database, especially if the database contains more than 4 GB of data.

To decrease the maximum size of the OSAM data sets to 4 GB:

Procedure

  1. If the database is already open in an online IMS system, stop access to the database by issuing either the /DBRECOVERY DB haldb_master command or the UPDATE DB NAME(haldb_master) STOP(ACCESS) command.
  2. Unload the data from all of the partitions in the database.
  3. Issue the CHANGE.DB command with the NOOSAM8G keyword.
  4. Split the partitions that contain any data sets that have more than 4 GB of data. Either define new partitions or rearrange the high key definitions of the existing partitions by using either the HALDB Partition Definition utility (%DFSHALDB) or DBRC commands.
  5. Initialize all of the partitions that are affected by the change by running either the HALDB Partition Data Set Initialization utility (DFSUPNT0) or the Database Prereorganization utility (DFSURPR0).
  6. Reload all of the partitions that are affected by the change by using the output from unloading the data from the database.
  7. Create image copies of the data sets in the affected partitions. DBRC does not allow updates to the data after the image copy required flag is set and before the image copies are recorded in the RECON data sets.
  8. Make the partitions available by issuing either the /START DB haldb_master command or the UPDATE DB NAME (partition_name) START(ACCESS) OPTION(OPEN) command.
The master database record in the RECON data set is updated to indicate that the HALDB supports 4-GB OSAM data sets.