Db2 Data Gate storage saver

The storage saver in Db2 Data Gate archives data of table partitions in Db2 for z/OS® to a Db2 Warehouse database on Cloud Pak for Data. By moving historical data that is no longer regularly used to a less expensive storage device, you can free up costly storage space on your Db2 for z/OS database server.

The storage saver not only frees up space on Db2 for z/OS, but also has the positive side-effect that it makes the database system more responsive. This is because fewer objects need to be maintained in the catalog, smaller or fewer indexes need to be searched, reorganizations become quicker, report data and statistics can be gathered faster.

Before the storage saver moves Db2 for z/OS data to the Db2 Warehouse target database and deletes the original data, Db2 image copies are created, which allow you to restore the data if needed. The table spaces of the affected (archived) partitions are set to a persistent read-only state, which prevents future INSERT, UPDATE, and DELETE operations on these partitions. Furthermore, the storage saver ensures that the data in the image copies is consistent with the data that is going to be archived.

Data that has been archived by the storage saver can always be queried if the query acceleration function is enabled. Mind, however, that the data to be queried is available in the target database only (Db2 Warehouse on Cloud Pak for Data) and not in Db2 for z/OS. This is also the reason why the query acceleration function must be enabled if you want to query archived data. For more information, see query acceleration.

In Db2 for z/OS, the table space of an archived partition continues to exist. It will be empty, but will still claim as much disk space as defined by the minimum primary space allocation.