Oracle Data Guard 11gR2 Administration Beginner's Guide

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Time for action – verifying the standby database configuration

Run the following actions to verify the standby database configuration and redo transport services:

Connect the standby database using SQL*Plus and check for the database role and status to ensure the database role is the physical standby.

SQL> select db_unique_name,database_role,open_mode from v$database;
DB_UNIQUE_NAME DATABASE_ROLE OPEN_MODE
--------------- ---------------- --------------------
india_un PHYSICAL STANDBY MOUNTED

Check the standby database, SPFILE.

SQL> show parameter spfile
NAME TYPE VALUE
------ ------- --------------------------------------------------
spfile string /u01/app/oracle/product/11.2.0/db_1/dbs/spfileINDIA.ora

Tip

If you have started the standby instance with PFILE, you should create an SPFILE and start an instance again using the new SPFILE.

Use the v$datafile view to check the location of the datafiles in the standby database. The standby database datafile must be under the /u02 directory because of the DB_FILE_NAME_CONVERT parameter setting.

SQL> select name from v$datafile;
NAME
---------------------------------------------
/u02/app/oracle/oradata/orcl/system01.dbf
/u02/app/oracle/oradata/orcl/sysaux01.dbf
/u02/app/oracle/oradata/orcl/undotbs01.dbf
/u02/app/oracle/oradata/orcl/users01.dbf
/u02/app/oracle/oradata/orcl/example01.dbf

Use the v$logfile view to check the location of online and standby redo logfiles in the standby database.

SQL> select group#,type,member from v$logfile;

 GROUP# TYPE MEMBER
---------- ------- ----------------------------------------------
 3 ONLINE /u02/app/oracle/oradata/orcl/redo03.log
 2 ONLINE /u02/app/oracle/oradata/orcl/redo02.log
 1 ONLINE /u02/app/oracle/oradata/orcl/redo01.log
 4 ONLINE /u02/app/oracle/oradata/orcl/redo04.log
 10 STANDBY /u02/app/oracle/oradata/orcl/standby_redo01.log
 11 STANDBY /u02/app/oracle/oradata/orcl/standby_redo02.log
 12 STANDBY /u02/app/oracle/oradata/orcl/standby_redo03.log
 13 STANDBY /u02/app/oracle/oradata/orcl/standby_redo04.log
 14 STANDBY /u02/app/oracle/oradata/orcl/standby_redo05.log

Note that the online redo logfiles and standby redo logfiles in the primary database are created under the /u01 directory, whereas logfiles in the standby database are under /u02. This change occurred because of the settings of the LOG_FILE_NAME_CONVERT parameter.

SQL> show parameter log_file_name_convert
NAME TYPE VALUE
---------------------- ----------- ----------------------------
log_file_name_convert string /u01/app/oracle/oradata/orcl,
 /u02/app/oracle/oradata/orcl

Verify if the redo transport service is active using the v$managed_standby view on the standby database:

SQL> SELECT THREAD#,SEQUENCE#,PROCESS,CLIENT_PROCESS,STATUS,BLOCKS FROM V$MANAGED_STANDBY;
 THREAD# SEQUENCE# PROCESS CLIENT_P STATUS BLOCKS
---------- ---------- --------- -------- ------------ ----------
 1 148 ARCH ARCH CLOSING 6
 1 147 ARCH ARCH CLOSING 8
 1 149 RFS LGWR IDLE 1
 0 0 RFS UNKNOWN IDLE 0

You must see RFS processes running on the standby database, which are responsible for writing redo information that the primary database sends to standby.

What just happened?

We've verified the standby database mode, status, and database files. We've also seen that the redo transport service is actively working between primary and standby.

Managing Redo Apply

As discussed in Chapter 1, Getting Started, Redo Apply is the synchronization method of the physical standby databases. Now let's see how can we start, stop, and monitor Redo Apply.