This step applies to coupling facility log streams only. For DASD-only log streams, duplexing to staging data sets is automatic.

Using the STG_DUPLEX and DUPLEXMODE parameters in the LOGR policy, you can request how you want system logger to duplex coupling facility resident log data for a log stream. You can duplex coupling facility data in either local storage buffers for each system or in DASD staging data sets. With z/OS® R2, another available option is to use the system-managed duplexing rebuild function for duplexing the coupling facility resident log data. The Logger log stream LOGGERDUPLEX parameter and your parallel sysplex configuration will determine whether Logger will duplex the log data or whether it uses the system-managed duplexing rebuild process using duplex-mode coupling facility structures.

The method you choose depends on whether your use of the log stream can tolerate a loss of data, whether your connection contains a single point of failure, and for duplex-mode structures whether there is a failure-independent relationship between two structure instances.