Replication logging
Replication logging is a form of logging in CICS® where updates to VSAM files, including RLS files, in one location are replicated on another site. In this way, multisite operations can reduce their recovery time objective (RTO) to near zero.
The replication is done by an external product that uses the replication log records CICS issues.
For replication logging with VSAM files, you can use system transaction CFCT to provide tie-up records for files to a replication log at specified intervals. For more information, see VSAM files.
To turn on replication logging, always use the IDCAMS LOGREPLICATE option. Do not use the CICS DEFINE FILE, SET FILE, or SET DSNAME commands.
| Options that can be defined in data sets | LOGREPLICATE | Results |
|---|---|---|
| RECOVERY(NONE) | No | No logging takes place. |
| RECOVERY(NONE) and Replication | Yes | UNDO, REDO, TIEUPS and FILE CLOSE records are written to the replication log. |
| RECOVERY(BACKOUTONLY) | No | UNDO records are written to the CICS system log. |
| RECOVERY(BACKOUTONLY) and Replication | Yes | UNDO records are written to the CICS system log. UNDO, REDO, COMMIT or BACKOUT, TIEUPS and FILE CLOSE records are written to the replication log. |
| RECOVERY(ALL) | No | UNDO records are written to the CICS system log. REDO, TIEUPS and FILE CLOSE records are written to the forward recovery log. |
| RECOVERY(ALL) and Replication | Yes | UNDO records are written to the CICS system log. UNDO, REDO, TIEUPS, COMMIT or BACKOUT and FILE CLOSE records are written to the joint forward and replication log. (The REDO, TIEUPS, and FILE CLOSE records are written once and contain indicators showing they are written for both forward recovery and replication). |