4 Monitoring Performance with Oracle Enterprise Manager

Overview of Oracle Enterprise Manager for Real Application Clusters

Enterprise Manager enables you to view current and past RAC database availability, performance metrics, and response times. Enterprise Manager can display this information at a high level for multiple cluster databases without requiring you to explicitly access each individual database.

Enterprise Manager supports monitoring at all levels of a cluster environment such as the cluster, the cluster database, and the cluster database instances. Enterprise Manager also responds to metrics from across the entire RAC database and publishes alerts when thresholds are exceeded. Enterprise Manager interprets both pre-defined or customized metrics. You can also copy customized metrics from one cluster database instance to another, or from one RAC database to another.

Enterprise Manager also uses data from the Automatic Workload Repository to display performance information and to initiate database alerts. Statistics that are collected by the Automatic Workload Repository are aggregated from all instances in a RAC database and displayed on a summary Enterprise Manager page.

Enterprise Manager provides performance information for:

• Top Sessions—The most time- and resource-consuming sessions, waits, and SQL statements at the cluster database instance level.

• Top Consumers—This includes Top Services, Top Modules, Top Actions by Module and Service, and Top Clients. This enables statistics aggregation, client identification support, and so on.

• Database Locks—Includes client identifiers, service modules, and actions.

• Cluster Cache Coherency—Performance information shows Global Cache Service (GCS) and Global Enqueue Service (GCS) activity

When you install RAC and create your RAC database with the Database Configuration Assistant (DBCA), the Enterprise Manager Database Control tools are pre-authorized to monitor your RAC environment. You can use Enterprise Manager Database Control to manage a single RAC database with its instance targets, listener targets, host targets, and cluster target. You can also install Enterprise Manager Grid Control onto servers either inside or outside your cluster and manage multiple RAC databases and multiple cluster targets.

Enterprise Manager Performance Pages for Real Application Clusters

Enterprise Manager displays both aggregate and instance-specific performance statistics using color-coded histograms. On any Enterprise Manager statistics display, highlight a statistic name on a statistics chart and Enterprise Managers re-displays the chart with colors for easier viewing. To obtain details about a highlighted statistic, click it and Enterprise Manager displays a detail page that provides more information about the statistic.

From the Cluster Database Home page you can access RAC-specific detail pages that show performance trends across one or more cluster databases. The following sections describe these pages in more detail:

• Using the Cluster Performance Page

• Using the Cluster Database Performance Page

• Using the Cluster Cache Coherency Page

• Using the Cluster Cache Coherency Instances Page

Service Relocation and High Availability Events

Enterprise Manager monitors events at the database and instance levels, and any available node can monitor database events. However, only one node at a time monitors the entire database while each node monitors events for its local instance.