Scenario 8: Monitoring a Data Guard Configuration

Enterprise Manager provides ways to monitor the status of a configuration as well as the online redo log file activity of the primary and standby databases. At the most basic level, the Data Guard Overview page for the configuration not only displays information about the configuration, but it also includes summary information about its databases.

For example, the summary information on the Data Guard Overview page shows the status for all of the databases in the configuration. If you want more information about why Redo Apply or SQL Apply are off for a specific standby database, select the Status link of the database in the Standby Databases table and view the property pages. Any Data Guard specific database properties that are incorrect, inconsistent, or known to be in conflict with other parameters will be flagged with a warning in the Edit Properties page for the database. A variety of icons indicating the status condition can appear next to the Status link. A green check mark appears if the primary database is

See Also: Section 5.4.3 for more information about post-failover steps to reenable databases

Note: You can access the monitoring functions of Data Guard even if you are logged in as a non-SYSDBA user. However, all management features, such as standby creation, switchover, and failover, require a SYSDBA connection.

Scenario 8: Monitoring a Data Guard Configuration

functioning normally; a yellow triangle containing an exclamation mark appears if there is a warning; and a red X appears if there is an error condition.

■ To check the primary database status, select Status under the Primary Database section of the Data Guard Overview page.

■ To check the status of a standby database listed in the Standby Databases table, select the link under the Status column.

For example, a yellow warning icon may display the message "A yellow warning indicates an inconsistent property has been detected. The value for this property is inconsistent between Data Guard and the database, Data Guard and the server parameter file, or Data Guard and both the database and server parameter file."

Figure 6–40 shows the Data Guard Overview page in the case where the configuration has returned an error because the observer is no longer observing the fast-start failover configuration.

Figure 6–40 Data Guard Overview Page Showing Observer Error

The following sections provide information on ways to monitor the status and health of a configuration:

■ Section 6.8.1, "Verifying a Broker Configuration"

■ Section 6.8.2, "Viewing Log File Details"

■ Section 6.8.3, "Monitoring Configuration Performance"

Scenario 8: Monitoring a Data Guard Configuration

6.8.1 Verifying a Broker Configuration

Another way to quickly check the overall health of a broker configuration is to run the Verify operation. The Verify operation performs a series of validation checks on the broker configuration, including a health check of each database in the configuration.

The checks include:

1. Shows the current data protection mode setting, including the current redo transport service settings for each database and whether or not the standby redo log files are configured properly. If standby redo log files are needed for any database, the Verify results will allow you to automatically configure them.

2. Validates each database for the current status.

3. Performs a log switch on the primary database and then verifies that the log file was applied on each standby database.

4. Shows the results of the Verify operation, including errors, if any. The Verify operation completes successfully if there are no errors and an online redo log file was successfully applied to at least one standby database.

5. Shows any databases or RAC instances that are not discovered. Undiscovered databases and instances could prevent a failover or switchover from completing successfully.

6. Detects inconsistencies between database properties and their corresponding values in the database itself. It also provides a mechanism for resolving these inconsistencies.

To verify the configuration, click Verify under the Additional Administration section of the Data Guard Overview page. See Figure 6–41. The Verify command displays a progress indicator. When the Verify operation completes successfully, the broker configuration is healthy, guarding the data, and ready for a switchover or failover.

Figure 6–41 Verifying the Configuration

Note: You can click Cancel at any time to stop the Verify operation.

Scenario 8: Monitoring a Data Guard Configuration

When the Verify operation completes successfully, the broker configuration is healthy, guarding the data and ready for a switchover or failover operation. The Verify processing page can be canceled at any time.

Figure 6–42 shows the results after the successful completion of the Verify operation.

Figure 6–42 Results of the Verify Command

6.8.2 Viewing Log File Details

For each standby database in the configuration, there is a table that shows the status of archived redo log files that were generated on the primary database but not received by the standby database, and for archived redo log files that were received but not applied to the standby database. This Log File Details page is useful to determine log file information when redo transport or log apply services are stopped. Under normal operations, each standby table is empty.

For example, if redo transport services go offline unexpectedly, the primary database continues to generate archived redo log files, but redo transport services will not send the archived redo log files to the standby databases. You can view the Log File Details page to find out which log files have not yet been received for each standby database.

On the Log File Details page, there is a Primary Current Log entry that indicates the log sequence number of the current log file on the primary.

For each standby database, redo transport and log apply information is displayed to help diagnose any log file buildup. Table 6–1 describes the columns for the standby table:

Table 6–1 Log File Details Page

Column Title Description

Log The log sequence number.

Scenario 8: Monitoring a Data Guard Configuration

Click Log File Details from the Data Guard Overview page to see the page shown in Figure 6–43.

Figure 6–43 Viewing Log File Details

6.8.3 Monitoring Configuration Performance

For more in-depth performance and monitoring, you can display detailed performance statistics for a broker configuration using performance charts that provide a graphical summary of all online redo log file activity in the configuration. The charts are refreshed based on a collection interval (the rate at which data is sampled from the primary database) that you can specify. The default collection interval is 30 seconds, which can be changed. See the online Help for detailed information about

performance sampling rates.

Not Received The log file has not been received.

Not Applied The log file has not been applied.

First Change # (SCN) The first system change number.

Last Change # (SCN) The last system change number.

Size (KB) The size, in kilobytes, of the log file.

Time Generated The time when the log file was generated.

Time Completed The time at which the log file was completed.

Table 6–1 (Cont.) Log File Details Page

Column Title Description

Scenario 8: Monitoring a Data Guard Configuration

The Performance Overview page collects performance related information from all of the databases in the configuration. All charts are represented by metrics. Typically, the charts show two hours worth of data. You can click any chart to view historical data (for example, 24 hours a day, 7 days a week, 31 days a month). Rates are calculated by determining the amount of redo (applied or generated) divided by the collection interval (default is 1 minute for the performance page, 5 minutes for metrics).

■ Redo Generation Rate -- This chart shows the redo generation rate (KB/sec) on the primary.

■ Lag Times -- Shows the Transport Lag (the approximate number seconds of redo not yet available on the standby database) and Apply Lag (The approximate number of seconds the standby is behind the primary database).

■ Apply Rate -- Displays the standby apply rate (KB/sec). The Current Redo Generation Rate shows the last value. The Apply Rate When Active value (last 3 logs, KB/sec) shows the actual apply rate when averaged over the last three log files.

■ Test Application -- The test application is a built in application which will generate a workload on the primary database. This is an easy way view the performance metrics when the primary database is under a load.

■ Overview -- Shows the primary database name and status. Click the status link to view the historical summary of the status metric. Note: the status on the

performance page is shown directly from the status metric which runs at 5 minute collection intervals. The status on the Data Guard Overview Page is always updated on every refresh.

Scenario 9: Using Metrics

Figure 6–44 Performance Page

The Performance Overview page begins charting information as soon as the page is displayed. Data will not be collected for any offline or disabled databases.