Monitoring Events That Affect the Standby Database

To prevent possible problems, you should be aware of events that affect a standby database and learn how to monitor them. Most changes to a primary database are automatically propagated to a standby database through archived redo logs and thus require no user intervention. Nevertheless, some changes to a primary database require manual intervention at the standby site.

Dynamic Performance Views (Fixed Views)

The Oracle database server contains a set of underlying views that are maintained by the server. These views are often called dynamic performance views because they are continuously updated while a database is open and in use, and their contents relate primarily to performance. These views are also called fixed views, because they cannot be altered or removed by the database administrator.

These view names are prefixed with either V$ or GV$, for example, V$ARCHIVE_DEST or GV$ARCHIVE_DEST.

Standard dynamic performance views (V$ fixed views) store information on the local instance. In contrast, global dynamic performance views (GV$ fixed views), store information on all open instances. Each V$ fixed view has a corresponding GV$ fixed view.

The following fixed views contain useful information for monitoring the Data Guard environment:

* V$ARCHIVE_DEST

Describes the archived redo log destinations associated with the current instance on the primary site. You can use this view to find out the current settings of your archived redo log destinations.
* V$ARCHIVE_DEST_STATUS

This view, an extension of the V$ARCHIVE_DEST view, displays runtime and configuration information for the archived redo log destinations. You can use this view to determine the progress of archiving to each destination. It also shows the current status of the archive destination.

* V$ARCHIVE_GAP

Provides information about archive gaps on a standby database. You can use this view to find out the current archive gap that is blocking recovery.

* V$ARCHIVED_LOG

Displays archived redo log information from the control file, including archived log names. This view gives you information on which log has been archived to where on your primary database. On the primary database, this view describes the logs archived to both the local and remote destinations. On a standby database, this view provides information about the logs archived to this standby database. You can use this fixed view to help you to track archiving progress to the standby system by viewing the applied field.

* V$DATABASE

Contains database information from the control file. You can use this view to quickly find out if your database is a primary or a standby database, as well as its switchover status and standby database protection mode.

* V$DATAFILE

Contains datafile information from the control file. You can query this fixed view to verify that the standby datafiles are correctly renamed after your standby database is re-created.

* V$DATAGUARD_STATUS

Displays and logs events related to Data Guard since the instance was started.

* V$LOG

Contains log file information from the online redo logs. You can use the information about the current online log on the primary database from this view as a reference point to determine how far behind your standby database is in receiving and applying logs.

* V$LOGFILE

Contains static information about the online redo logs and standby redo logs.

* V$LOG_HISTORY

Contains log history information from the control file, including a record of the latest archived log that was applied.

* V$MANAGED_STANDBY

Displays current and status information for some Oracle database server processes related to Data Guard. This view can show both foreground and background processes. You can use this view to monitor the various Data Guard recovery and archiving processes on the standby system.

* V$STANDBY_LOG

Provides information about the standby redo logs. Standby redo logs are similar to online redo logs, but they are only used on a standby database receiving logs from the primary database using the log writer process.

regards,
rajeshkumar govindarajan

source and reference:
http://www-css.fnal.gov/dsg/external/oracle_dcm/9iv2/server.920/a96653/sbydb_manage_ps.htm

related topics:
Determining Which Logs Have Not Been Received by the Standby Site