Replication functional entities

SMF user records are constructed to report on the functional entities, not on the z/OS® tasks that are executing. The following functional entities are found in CDC for Db2® for z/OS.

System - Tasks that carry out necessary environment management processing that is not directly related to ongoing replication or which serves all ongoing replication simultaneously.

Source-side subscription - Tasks that obtain Db2 log data, organize it, and submit it for transmission to the target system, along with information that assists in the seamless restarting of the subscription.

Target-side subscription - Tasks that accept transmitted replicated table rows, process them for column transformation and user exit handling, and create the apply SQL. These tasks also attend to issues related to deadlock and time-out handling, and restart management.

Log Data Cache - Tasks that obtain Db2 log data and hold it in a cache so that multiple concurrent source-side subscriptions are able to use that data without having to re-obtain it from Db2.

The task types that cooperate within the different functional entities are:

System - OSC, PAL, CIT, PAA, DSC, CMO, CLS, CCI, CCO CVF, and MAA.

Source-side subscription - When the record segments' status modifier fields (SGHENSTM) have any of the SGHSMMRR bits set: DSL, CDI, CDO, SCT, and SDT. When the record segments' status modifier fields (SGHENSTM) have any of the SGHSMRFS bits set: CDI, CDO, SCT, and SDT.

Target-side subscription - DTC, CDI, CDO, TCT, and TDT.

Log Data Cache - DLR and DCW.

The task data segments for the task types that are described earlier appear in the SMF user records for the functional entities.