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Spotlight on Oracle 10.7 - Getting Started Guide

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Services By Instance

Note: Available for Oracle 10.2 and later.

The Services By Instance page summarizes the current load associated with the services deployed on the Oracle RAC cluster.

To open the Services By Instance page

  1. Select the Spotlight on Oracle RAC connection in the Spotlight Browser.

  2. Click Services.

Charts on the Services page

Notes:

  • Every chart has a legend (list of symbols) to its right that describes the various series (line graphs) on the chart.
  • Click an item in the legend to highlight its series (line) in the chart. Click a second time to return the series to its normal appearance.
  • Move the mouse pointer over an item in the legend to view the current value for that series within the chart.
Chart Description
CPU

CPU shows the rate (in milliseconds per second) at which CPU time is consumed by each service for all sessions on the database. Among the services deployed are:

  • A default Oracle database service.
  • The internal SYS$BACKGROUND service used by background processes.
  • The internal SYS$USERS service for user sessions not associated with an application service.

The aggregated CPU time for all services cannot exceed (1000 ms/s) x (the number of CPUs on the cluster).

DB Time

DB Time shows the rate (in milliseconds per second) at which elapsed time is spent in database user calls by the specified services.

DB time includes all wait time, and does not have the same limitations as CPU time. Because in theory ALL sessions may be waiting at the same time, the aggregated DB Time for all services can be as much as (1000 ms/s) x (the number of sessions connected).

There will always be some sessions connected on each instance in the cluster — even before a user logs in.

Logical Reads

Logical Reads shows the rate of logical reads for the specified services across the instances in the Oracle RAC cluster.

A logical read occurs when Oracle finds data in the local buffer cache of an instance without needing to read the data from physical disk. The rate of logical reads can be used to measure the balance between the instances in a cluster.

Physical Reads

Physical Reads shows the rate of physical reads for the specified services across the instances in the Oracle RAC cluster.

A physical read occurs when a database instance retrieves data from datafiles on the shared disk subsystem, and occurs every time a logical read fails to find the requested page in local or global cache.

Actions on the Services Page

Use the Chart Orientation control to display each chart in one of two ways:

Orientation Description
Services by Instance
  • The X-axis displays Units per Second for each chart.
  • The list of services is arranged on the Y-axis.
  • There are separate data series for each database instance in the Oracle RAC cluster.
Instances by Service
  • The X-axis displays Units per Second for each chart.
  • The database instances are arranged on the Y-axis.
  • There are separate data series for each service on the database cluster.

 

Related Topics

Spotlight on Oracle RAC Drilldowns

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