Time for action – enabling Active Data Guard if the standby database is shut down
If the standby database is completely shut down, use the following steps to enable Active Data Guard. Now start the database normally as follows:
[oracle@oracle-stby ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on Tue Nov 6 12:13:27 2012
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup
ORACLE instance started.
Total System Global Area 818401280 bytes
Fixed Size 2217792 bytes
Variable Size 528484544 bytes
Database Buffers 285212672 bytes
Redo Buffers 2486272 bytes
Database mounted.
Database opened.
SQL>
Once the database is opened successfully, by default it will be in the Read Only mode because it's a standby control file. Now start Redo Apply as follows:
SQL> select db_unique_name,open_mode from v$database;
DB_UNIQUE_NAME OPEN_MODE
--------------- --------------------
INDIA_UN READ ONLY
SQL>
SQL> alter database recover managed standby database using current logfile disconnect from session;
Database altered.
SQL>