MAA - Oracle 10gR2 Redo Transport and Network Best Practices

Maximum Availability Architecture
APPENDIX A: ENABLING ACTIVE DATA GUARD ON A STANDBY
DATABASE THAT REQUIRES ADDITIONAL RECOVERY
The process of enabling Active Data Guard is as simple as opening the standby
read-only and starting Redo Apply. This is true as long as the standby database is
in a consistent state. However, if the standby is in an inconsistent state, you must
make the standby consistent before opening the standby read-only. The reasons
why a standby database may be in an inconsistent state include:
• This is a newly created standby that has not yet started Redo Apply
• The standby instance and Redo Apply aborted or stopped due to an error
state
• The standby instance has newly restored data files
• The standby instance has a new standby controlfile
When a standby is inconsistent, you must perform a certain amount of media
recovery to bring the standby database and the standby control file to a consistent
state. You can enable Active Data Guard on an inconsistent standby database
using SQL*Plus statements or the Data Guard broker.
To use SQL*Plus statements to enable Active Data Guard on an inconsistent
standby database, perform the following steps:
1. Bring the standby database to the mount state:
SQL> startup mount
2. Start Redo Apply:
SQL> recover managed standby database disconnect;
3. Cancel Redo Apply after recovery has progressed:
SQL> recover managed standby database cancel;
4. Open the standby database read-only:
SQL> alter database open read-only;
5. Start Redo Apply:
SQL> recover managed standby database disconnect using current
logfile;
To use the Data Guard broker to enable Active Data Guard, use the following
procedure:
1. Bring the standby database to the mount state:
SQL> startup mount
2. With the Data Guard Broker, by default the database state for a standby is
APPLY ON and Redo Apply starts automatically once the database is
Oracle Active Data Guard: Oracle Data Guard 11g Page 21