Data Guard creation of logical standby Tips
Oracle Database Tips by Donald BurlesonDecember 9, 2015
Oracle Data Guard
Simplified creation of logical standby in 10g
In earlier releases, it was difficult to create
the logical Oracle instance
without shutting down the primary
database. If the online backup was used to create the logical
standby, a quiesce of the database at the end of backup is needed,
which also required the resource manager. The SCN must also be
recorded. These actions necessitated the primary database shutdown.
With Oracle Database 10g, there is no
need to quiesce the primary database. The required information is
read through the logical standby control file. Oracle recommends the
use of a new method to create a logical Oracle instance
his new method will allow the DBA to achieve
'zero down time instantiation' by using an online backup of the
primary database and the logical standby control file.
The suggested steps are as follows:
Take an online backup of the
primary database. Optionally, the offline backup of the primary
database can be used. If the offline backup is used, all the
archive log files from the time of the backup are needed.
After the backup is obtained,
create a logical standby control file with the newly provided CREATE
LOGICAL CONTROL FILE command. For example, use the following
ALTER DATABASE CREATE LOGICAL STANDBY CONTROL
FILE AS 'mylogicalstandby.ctl';
The logical standby control file is similar to
the physical control file but has additional information.
Copy all the backup files, archive
files, and logical standby control files to the standby host.
After restoring all the files,
mount the Oracle instance
with the logical standby control file.
Set up the log transport services
on the primary.
Start the managed recovery on the
standby database. Execute the following statement.
ALTER DATABASE RECOVER MANAGED STANDBY
Then, begin applying the redo logs.
To start the log apply services, execute the statement:
ALTER DATABASE START LOGICAL STANDBY APPLY;