Primary storage full condition for Logstreams

When a system logger user issues the IXGWRITE macro for a Logstream, system logger writes data to primary storage. When the write completes, system logger categorizes the event as a type-1, type-2, or type-3 completion. These categorizations indicate how much space in the primary storage is being used by the Logstream when the IXGWRITE completion occurred. Field SMF88SC1 indicates a type-1 event, SMF88SC2 a type-2 event, and SMF88SC3 a type-3 event. SMF88SC3 will only be maintained for structure based Logstreams. It is not defined for DASDONLY Logstreams and will contain zero.

• A type-1 completion (field SMF88SC1) indicates that after the write completed, the percentage of resource in use by the primary storage was less than the high offload threshold.
• A type-2 completion (field SMF88SC2) indicates that after the write completed, the percentage of resource in use by the primary storage was equal to or greater than the high offload threshold, so system logger begins managing storage resources by migrating data from the coupling facility to DASD.
• A type-3 completion (field SMF88SC3) indicates that a given log stream is close to consuming all the coupling facility structure space or if the system logger configuration is tuned incorrectly. For example, access to the system logger DASD log data sets would be slowed if those data sets reside on the same device as some other heavily-used data sets. A type-3 completion can also occur if many Logstreams are defined to share the same structure, because each newly defined Logstream causes system logger to dynamically repartition storage among the existing Logstreams. If a log stream has a large proportion of type-3 completions, system logger is getting dangerously close to the STRUCTURE FULL condition. SMF88SC3 will not be defined for DASDONLY Logstreams.