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Don Burleson Blog 







OEM RAC Monitoring

Oracle Database Tips by Donald Burleson

This is an excerpt from the bestselling Grid book Oracle 10g Grid & Real Application Clusters, by Mike Ault and Madhu Tumma. 

Monitoring and Tuning RAC using OEM

The first part of this chapter covered the manual aspects of RAC tuning, showing techniques and providing scripts to obtain the needed information from the various underlying Oracle views. This section will cover the tools provided by Oracle in the Oracle Enterprise manager (OEM) Performance Monitor. In order to use OEM to monitor a RAC environment, the following must be in place:

n        OEM installed.

n        OEM repository.

n        Oracle Intelligent Agents running.

Normally, if the standard installation is used, OEM will be installed as a matter of course. If possible, the OEM and its repository should be set up on a separate system, such as a small Windows-based server. At the least, a small repository database should be created on one of the RAC servers. This can be used for the RMAN repository as well.  The OEM client software can be installed on any desktop as long as that desktop has SQL*Net connectivity to the OEM repository.

The most difficult part of the setup for OEM is probably getting the intelligent agents to work properly with the RAC environment.

Configuring the OEM Oracle Intelligent Agent with RAC

In order to be sure that the agent is installed properly in Oracle Database 10g, the following MOSC documents should be reviewed:

n        EM 10g Database Control Release Notes Note: 266770.1

n        EM 10g GRID Control Release Notes Note: 266769.1

n        How to Log and Trace the EM 10g Management Agents Note: 229624.1

n        How To Install The Downloadable Central Management Agent in EM 10g Grid Control Note: 235287.1

The nodes and databases must be properly discovered and viewable from the OEM webpage before they can be monitored.

Using OEM for RAC in Oracle Database 10g

In 10g, Oracle is moving to the web based interface for EM and will soon deprecate the Java based version. Monitoring and management functions should be migrated into the HTML Web based version of EM as soon as possible. The following sections will provide a quick look at the screens in the new HTML version that the DBA should be using for RAC monitoring and management.

The Cluster Performance Page

In the HTML based web version of the EM, the Cluster Performance Page is used to display the usage statistics for all RAC hosts or for individual RAC hosts. This information allows you to add, suspend, or redistribute resources as the need arises. Figure 14.1 shows this page.


Figure 14.1: Example Cluster Performance Page

The Cluster Database Performance Page

The Oracle Database 10g EM Cluster Database Performance Page displays statistics via charts that show run queue length, paging rate, service time, and the database throughput for each RAC host or RAC instance. The page is also used to access the detailed information for the Wait Class Page for Service Time and the Top Sessions Page for Database Throughput. Figure 14.2 shows an example of this page.


Figure 14.2: Example Cluster Database Performance Page

The Cluster Cache Coherency Instances Page

The Cluster Cache Coherency Instances Page is used to provide real-time monitoring of global cache statistics. The Cluster Cache Coherency Instances Page will display tables of metrics from the following groups for all cluster instances:

n        Block Access Statistics

n        Global Cache Convert, Global Cache Current Block Request, Global Cache CR

n        Block Request

n        Top 5 Library Cache Lock and Top 5 Row Cache Lock

Figure 14.3 shows the Cluster Cache Coherency Page:


Figure 14.3: Example Cluster Cache Coherency Page

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

By using the various screens and reports in OEM Performance Manager for RAC, the status of virtually any section of the RAC environment can be seen. The screens and reports provide suggestions to correct problems as they occur.


If you like Oracle tuning, you may enjoy my new book "Oracle Tuning: The Definitive Reference", over 900 pages of BC's favorite tuning tips & scripts. 

You can buy it direct from the publisher for 30%-off and get instant access to the code depot of Oracle tuning scripts.



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Note: This Oracle documentation was created as a support and Oracle training reference for use by our DBA performance tuning consulting professionals.  Feel free to ask questions on our Oracle forum.

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