System logger

The system logger is a z/OS® component that allows an application to log data from a sysplex environment. Data can be logged from one z/OS system or from multiple systems across the sysplex.

The z/OS system logger is a set of services that allows an application to write, browse, and delete log data. You can merge the log data from applications in a sysplex into a log stream, which is simply a collection of data in log blocks residing in the coupling facility; as the coupling facility fills, older data might be off-loaded to archival log stream data sets on DASD. Log blocks in the coupling facility can be backed up either in storage in each system or on DASD in staging data sets. When the log blocks in the coupling facility reach an installation-defined threshold value, they are off-loaded to DASD log data sets. Therefore, at any point in time, the log stream consists of records on the DASD log data sets (where data is hardened for longer term access) and the log blocks that currently reside in the coupling facility.

A system logger configuration includes the system logger address space in each system, the LOGR couple data set, a log stream structure in a coupling facility, DASD log data sets for off-loaded data from the coupling facility log stream, and optionally staging data sets for a backup copy of the log blocks resident in the log stream structure.

The system logger address space provides the application with services and connections to the coupling facility. An installation must:

1. Plan and predefine the coupling facility structures
2. Format and define a policy for the LOGR couple data set.
3. Define the DASD log data sets.
4. Optionally create staging data sets.