5.1 Monitoring Oracle Clusterware with Oracle Enterprise Manager

Use Oracle Enterprise Manager to monitor the Oracle Clusterware environment.

When you log in to Oracle Enterprise Manager using a client browser, the Cluster Database Home page appears where you can monitor the status of both Oracle Database and Oracle Clusterware environments. Oracle Clusterware monitoring includes the following details:

  • Current and historical Cluster Health Monitor data in Oracle Enterprise Manager on the cluster target

  • Notifications if there are any VIP relocations

  • Status of the Oracle Clusterware on each node of the cluster using information obtained through the Cluster Verification Utility (CVU)

  • Notifications if node applications (nodeapps) start or stop

  • Notification of issues in the Oracle Clusterware alert log for the Oracle Cluster Registry, voting file issues (if any), and node evictions

The Cluster Database Home page is similar to a single-instance Database Home page. However, on the Cluster Database Home page, Oracle Enterprise Manager displays the system state and availability. The system state and availability includes a summary about alert messages and job activity, and links to all the database and Oracle Automatic Storage Management (Oracle ASM) instances. For example, track problems with services on the cluster including when a service is not running on all the preferred instances or when a service response time threshold is not being met.

Use the Oracle Enterprise Manager Interconnects page to monitor the Oracle Clusterware environment. The Interconnects page displays the following details:

  • Public and private interfaces on the cluster

  • Overall throughput on the private interconnect

  • Individual throughput on each of the network interfaces

  • Error rates (if any)

  • Load contributed by database instances on the interconnect

  • Notifications if a database instance is using public interface due to misconfiguration

  • Throughput contributed by individual instances on the interconnect

All the information listed earlier is also available as collections that have a historic view. The historic view is useful with cluster cache coherency, such as when diagnosing problems related to cluster wait events. Access the Interconnects page by clicking the Interconnect tab on the Cluster Database home page.

Also, the Oracle Enterprise Manager Cluster Database Performance page provides a quick glimpse of the performance statistics for a database. Statistics are rolled up across all the instances in the cluster database in charts. Using the links next to the charts, you can get more specific information and perform any of the following tasks:

  • Identify the causes of performance issues

  • Decide whether resources must be added or redistributed

  • Tune your SQL plan and schema for better optimization

  • Resolve performance issues

The charts on the Cluster Database Performance page include the following:

  • Chart for Cluster Host Load Average: The Cluster Host Load Average chart in the Cluster Database Performance page shows potential problems that are outside the database. The chart shows maximum, average, and minimum load values for available nodes in the cluster for the previous hour.

  • Chart for Global Cache Block Access Latency: Each cluster database instance has its own buffer cache in its System Global Area (SGA). Using Cache Fusion, Oracle RAC environments logically combine buffer cache of each instance to enable the database instances to process data as if the data resided on a logically combined, single cache.

  • Chart for Average Active Sessions: The Average Active Sessions chart in the Cluster Database Performance page shows potential problems inside the database. Categories, called wait classes, show how much of the database is using a resource, such as CPU or disk I/O. Comparing CPU time to wait time helps to determine how much of the response time is consumed with useful work rather than waiting for resources that are potentially held by other processes.

  • Chart for Database Throughput: The Database Throughput charts summarize any resource contention that appears in the Average Active Sessions chart, and also show how much work the database is performing on behalf of the users or applications. The Per Second view shows the number of transactions compared to the number of logons, and the amount of physical reads compared to the redo size for each second. The Per Transaction view shows the amount of physical reads compared to the redo size for each transaction. Logons is the number of users that are logged on to the database.

In addition, the Top Activity drop-down menu on the Cluster Database Performance page enables you to see the activity by wait events, services, and instances. In addition, you can see the details about SQL/sessions by going to a prior point in time by moving the slider on the chart.