Watch support enhances the trace functions in i5/OS® by automatically monitoring and ending traces when certain predetermined criteria are met. This prevents the loss of valuable trace data and reduces the amount of time you need to spend monitoring traces.
For example, when you start a trace on a busy system, it is possible for large amounts of trace data to be collected very quickly so that the trace buffer wraps, overlaying previous trace data. By the time you can manually determine the problem has occurred and stop the trace, the previous trace data needed to solve the problem has been overlaid. The result is lost trace data. The watch function solves this problem by allowing you to set certain watch criteria using the watch parameters. When a failure occurs, there is often a message or a Licensed Internal Code log that is generated at the time of the failure. You can specify which messages or Licensed Internal Code logs should be monitored during the trace collection, and when they occur the system automatically ends the trace.