CICS VSAM Transparency for z/OS, Version 1.2


Process overview

The CICS VT DIM and DDM driver modules are generated when the mapping of a data set is complete. The driver modules and the DDM DBRM need to be copied to the target system. The mapping data in the CICS VT system tables is only used again if you change mapping, after which new driver modules should be generated.

The DDM driver includes the SQL used to access the DB2 data. This SQL is dependent on the attributes of the DB2 table containing the migrated VSAM data. This means that the DB2 table must be identical in each target system. The CREATOR can vary, but the table name, column names, and attributes must be the same. The DBRM produced during DDM generation must be copied to the target system and bound against the DB2 objects that will contain the VSAM file data.

The key objectives of the cutover are to ensure that the period when the files are unavailable is kept to a minimum, and that there is no adverse effect on service levels. To achieve these objectives, the cutover process is split into three phases:

  1. Pre-cutover tasks
  2. Cutover tasks
  3. Post-cutover tasks

If you are unable to complete the cutover successfully, or you encounter severe post-cutover problems, you might decide to fall back to VSAM. A method to fallback to VSAM is described in Fall back to VSAM.





Last updated: November 9, 2012 20:42:52