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

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.

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

Scenario 8: Monitoring a Data Guard Configuration

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. Status The status of the log file.

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.

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.

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

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

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

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.

6.9 Scenario 9: Using Metrics

Oracle Enterprise Manager automatically monitors the status and redo log file activity on the primary and standby databases. The following list shows the Data Guard metrics:

■ Data Guard Fast-Start Failover: – Fast-Start Failover Occurred

– Fast-Start Failover SCN

– Fast-Start Failover Time ■ Data Guard Performance

– Apply Lag (seconds)

– Estimated Failover Time (seconds)

– Redo Apply Rate (KB/second)

– Transport Lag (seconds) ■ Data Guard Status

You can set up Email Services to notify you through your e-mail if any of the metrics are triggered.

6.9.1 Understanding the Data Guard Metrics

The following sections provide additional information about the Data Guard metrics.

6.9.1.1 Fast-Start Failover Metrics

When fast-start failover is enabled, these metrics will generate a critical alert on the new primary database (old standby) if a fast-start failover occurs.

6.9.1.2 Data Guard Performance Metrics

The Data Guard performance metrics provide alerts for performance related to redo log activity in the configuration.

6.9.1.3 Data Guard Status

The Data Guard Status metric checks the status of each database in the broker configuration and triggers a warning or critical alert if necessary.

6.9.2 Managing Data Guard Metrics

The example in this section describes Data Guard metrics and how to set up for notification through e-mail when a metric is triggered. Take the following steps to manage Data Guard metrics: