Using Oracle Enterprise Manager (OEM) to Monitor Real-Time Database Performance

Oracle Enterprise Manager (OEM) can be used to monitor databse performance in real time and show us where we need to focus our attention.  The performance page presented in OEM gives three distinct sections that one can look at and get an overall performance picture of the database in real time and then can subsequently drill down into other pages to get at root causes of performance problems.

Monitoring User Activity: From the performance page, DBAs can take a look at the active session over a period of time and drilling down for those sessions that are of interest, either those running on the CPU or waiting on an event.

Monitoring instance activity: Monitor instance activity through the instance chart/graph to monitor throughput, I/O, parallel execution, and services.

Monitoring Host Activity: Monitoring host activity is important because it contains information about the system that is hosting the database. If there isn't enough memory, disk or CPU, then this is where it will show up.

In the performance page, DBAs can set a refresh rate, refresh on demand, and view the data behind the graphs. This screen shows at a glance CPU utilization at the top under the “Host: Runnable Processes” graph, a breakdown of the “Average Active Session” types, and another graph showing the instance throughput rate, selectable by per second or per transaction, for transactions and physical read and redo activity.

For further investigation, DBAs can manually run ADDM to analyze immediately instead of waiting for the next scheduled Automatic Workload Repository (AWR) snapshot to run.