z/OS databases

Compress Db2 large object (LOB) table spaces, archive logs, and IBM Content Manager OnDemand archives to achieve faster query response times, reduced disk use, and improved archive performance.

Compressing LOB data with zEDC can reduce the size of data in a LOB table space and ensure that the LOB table space and its associated base table space remain available for longer. For more information, see COMPRESS DIRLOB.

If you have been using zEDC with the zEDC Express adapter, review the definitions, including ARS.CFG parameters for Content Manager OnDemand, and consider applying compression more broadly. For more information on ARS.CFG parameters, see ARS.CFG parameters.

If you have not been using zEDC, enable compression for individual table spaces by specifying the COMPRESS YES option on the CREATE TABLESPACE or ALTER TABLESPACE statement. For more information, see CREATE TABLESPACE. Enable compression for the Db2 directory by setting the COMPRESS_DIRLOB subsystem parameter to YES.

Assessing compression: After testing the Db2 application that uses LOB data, you can assess the compression by:
  • Checking the size of the table space in Db2 once compression is used
  • SMF record type 30. See the discussion of record type 30 in Assess compression of z/OS data.