With interval accounting, you specify an interval of time called a recording interval. This interval repeats continuously, starting when a unit of work begins to run. Interval accounting allows you to periodically save resource data for the work unit so that, if a system failure occurs, not all of this data is lost.
A work unit (such as a job or job step) uses system resources to accomplish its tasks. As the work unit runs, the system saves data about the resources that it uses at the end of each recording interval. If the system fails during an interval, you do not lose the resource data generated through the end of the previous interval. Only the data accumulated since the end of the last interval is lost.
Example: Assume that you specify an interval of 30 minutes, that a job starts at 9:10 and runs for an hour and 42 minutes, and that the job uses resources as follows:
| Time | Action | Resources Used Since Job Start | Resources Used During Interval |
|---|---|---|---|
| 9:10 AM | job starts | — | — |
| 9:40 AM | 30 minute interval ends | 7 | 7 |
| 10:10 AM | 30 minute interval ends | 12 | 5 |
| 10:40 AM | 30 minute interval ends | 21 | 9 |
| 10:52 AM | job ends | 23 | 2 |
Interval accounting allows you to see how many resources the work unit used during a specified interval of time. In this example, the job used 5 resources between 9:40 and 10:10 AM (a 30-minute interval) and used a total of 12 resources since the job started.