Both CICS® VR
forward recovery logging and undo logging write to MVS™ system logger log streams.
Both DASD-only log streams and coupling facility log streams, or a combination
of both are supported, as described below:
- DASD-only logging
- Use DASD-only log streams when
you do not have access to or do not want to use a coupling facility for logging.
DASD-only log streams can only be single-system in scope; only one system
can connect to a DASD-only log stream.
- Coupling facility logging
- Use
coupling facility logging if you have applications that run on multiple systems
in the sysplex and require a single sysplex-wide log stream. A coupling facility
is required to merge the data from multiple systems into a single log stream.
- Combination of coupling facility logging and DASD-only logging
- You can use a combination of coupling facility logging and DASD-only logging
if you use a coupling facility. You can have applications that run on multiple
systems in the sysplex that require the log records to be merged into a single
log stream. You can also have applications that require separate DASD-only
log streams for each system. The coupling facility manages both the coupling
facility logging and the DASD-only logging in the sysplex.
To
help you decide which type of log stream is right for you, see z/OS® MVS Setting Up
a Sysplex. This book also contains detailed information on how to set
up the coupling facility resource management policy (CFRM policy) and the
LOGR couple data set (LOGR policy).
Any logstream that CICS VR VSAM
batch logging writes to is automatically registered in the CICS VR RCDS.
Therefore, information about the log streams can be viewed through the CICS VR
log stream list of the CICS VR ISPF panel interface.
In addition, a
retention period can be specified for all registered log streams. If specified, CICS VR
deletes log blocks from all registered log streams that are older than the
specified retention period. See Understanding CICS VR automatic deregistration for
more information.