New Background Processes

In Oracle Database 10 g , two new background processes are responsible for collecting, sampling, and maintaining the statistical data. These processes are the MMON and MMNL.

The MMON (Manageability Monitor) process is responsible for various manageability tasks such as taking snapshots of various statistical information at prescribed time intervals and issuing alerts when metric values exceed defined thresholds. The MMON process can spawn multiple slave processes to perform these tasks .

The MMNL (the Manageability Monitor ‚ Lightweight) process is responsible for computing various metrics and taking snapshots of active sessions at every second. We ‚ ll discuss this further in the section ‚“Active Session History. ‚½

Note ‚  

The database instance does not crash when MMON or MMNL process is terminated for whatever reason. The PMON process will restart the failed process. Relevant messages will be written to the alert log file.

So, how does Oracle Database 10 g actually collect, report, and maintain the performance statistics data? This is collectively done by the Automatic Workload Repository.