Time for action – enabling Active Data Guard if Redo Apply is running using SQL *PLUS

1. If you have previously upgraded your database from Version 10gRx to 11gRx, then in order to use Active Data Guard the compatible parameter must at least be set to 11.0.0 as shown in the following query:

   SQL> show parameter compatible
   NAME                                 TYPE        VALUE
   ------------------------------- ----------- --------------------
   compatible                           string      11.2.0.0.0

2. If you are using Active Data Guard for the first time, your standby database will definitely be in the MOUNT status and MRP will be in progress; hence, cancel MRP. After cancelling MRP, make sure MRP is not running any more either through the OS level grep commands or the v$managed_standby view as shown in the following query:

   SQL> select db_unique_name,open_mode from v$database;
   DB_UNIQUE_NA OPEN_MODE
   ------------ --------------------
   INDIA_UN     MOUNTED
   SQL> alter database recover managed...