Changing the OLDS mode from single to dual

You must change your OLDSDEF specification in the LOGGER section of the DFSDFxxx member in IMS.PROCLIB to change the OLDS mode from single to dual. IMS initialization requires that at least three pairs of OLDSs be available for a dual logging environment. You must also reconsider data set placement.

When changing from single to dual OLDS, each data set in a pair of OLDSs must have the same space allocation (number of blocks).

Changing the mode from single to dual or from dual to single requires changes in the following operating procedures:

  • Skeletal JCL for archive (ARCHJCL member)
  • Skeletal JCL for log recovery (LOGCLJCL member)
  • Batch JCL for Log Recovery utility
  • Batch backout JCL for online transactions and BMPs

If you warm start the IMS subsystem after changing from single to dual OLDSs, the /DISPLAY OLDS command does not show the secondary OLDSs as IN USE until they have been archived once. The command does, however, show dual OLDS logging.

Procedure

  1. Shut down IMS.
  2. Archive all OLDSs.
  3. Allocate dual OLDSs.
  4. Delete the OLDS records from the RECON data sets, using the DELETE.LOG command. The primary OLDS records will be deleted.
  5. Change OLDSDEF specification to dual.
  6. Change IMS startup procedure (OLDS DD statements), if required.
  7. Compile DFSMDA macros, if required.
  8. Modify operating procedures.
  9. Restart IMS.