If you prefer, you can set a delay between the arrival of the archived redo log and it being applied on the standby server using the following commands. Provided you have configured standby redo logs, you can start real-time apply using the following command. By default, for a newly created standby database, the primary database is in maximum performance mode.
The mode can be switched using the following commands. Note the alterations in the redo transport attributes. A database can be in one of two mutually exclusive modes primary or standby. These roles can be altered at runtime without loss of data or resetting of redo logs. This process is known as a Switchover and can be performed using the following statements. Once this is complete, test the log transport as before. If everything is working fine, switch the primary database back to the original server by doing another switchover.
This is known as a switchback. If the primary database is not available the standby database can be activated as a primary database using the following statements. The original primary database can now be configured as a standby. If Flashback Database was enabled on the primary database, then this can be done relatively easily shown here.
If not, the whole setup process must be followed, but this time using the original primary server as the standby.
It was already mentioned in the previous section, but it is worth drawing your attention to Flashback Database once more. If flashback database is not enabled, the original primary must be scrapped and recreated as a standby database. An alternative is to enable flashback database on the primary and the standby if desired so in the event of a failover, the primary can be flashed back to the time before the failover and quickly converted to a standby database.
That process is shown here. Once a standby database is configured, it can be opened in read-only mode to allow query access. This is often used to offload reporting to the standby server, thereby freeing up resources on the primary server.
In the "Creation Options" screen Figure , click Finish. In the "Confirmation" screen Figure , review the selected options, then click OK. Allow the database creation tasks to complete Figure If any one of the tasks fails, remedy the problem before continuing.
Open a browser and go to the URL highlighted in bold in step a above. If you see a "Security Mismatch" error, ignore it the error appears if you are using a self-signed certificate.
Click Create near the top right corner of the user list Figure In the "Create User" form Figure , fill in all required fields marked with an asterisk. Fill in all other fields as necessary. Select the default and temporary tablespaces for the new user Figure Do the following:. In the "Create User" form, click the flashlight button next to the Default Tablespace field. In the "Create User" form, click the flashlight button next to the Temporary Tablespace field.
In the "Available Roles" list, select the required roles and click Move. This process is known as a Switchover and can be performed using the following commands.
Let's switch back to the original primary. If the primary database is not available the standby database can be activated as a primary database using the following statements.
The original primary database can now be configured as a standby. If flashback database was enabled on the primary database, then this can be done relatively easily with the following command. If flashback database is not enabled, you would have to manually recreate db11g as a standby. The basic process is the reverse of what you did previously. It was already mentioned in the previous section, but it is worth drawing your attention to Flashback Database once more.
If flashback database is not enabled, the original primary must be scrapped and recreated as a standby database. An alternative is to enable flashback database on the primary and the standby if desired so in the event of a failover, the primary can be flashed back to the time before the failover and quickly converted to a standby database, as shown above.
Once a standby database is configured, it can be opened in read-only mode to allow query access. This is often used to offload reporting to the standby server, thereby freeing up resources on the primary server. When open in read-only mode, archive log shipping continues, but managed recovery is stopped, so the standby database becomes increasingly out of date until managed recovery is resumed.
In 11g, Oracle introduced the Active Data Guard feature. This allows the standby database to be open in read-only mode, but still apply redo information. This means a standby can be available for querying, yet still be up to date.
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