Enable or Disable Archivelog Mode in Oracle 11g Database

Enable Archivelog Mode 

Step 1:- Log on to the database and check archivelog mode for database

[oracle@pract1 fra]$ sqlplus "/ as sysdba"

SQL*Plus: Release 11.2.0.1.0 Production on Thu Jul 28 18:03:43 2016

Copyright (c) 1982, 2009, Oracle.  All rights reserved.

Connected to:

Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production

With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> select instance_name, status from v$instance;

INSTANCE_NAME    STATUS

---------------- ------------

KMDB             OPEN

SQL> archive log list

Database log mode              No Archive Mode

Automatic archival             Disabled

Archive destination            /u01/app/oracle/product/11.2.0/dbhome_1/dbs/arch

Oldest online log sequence     1

Current log sequence           2

Step 2:- Looks like archivelog destination parameter is set to default location. We will change the archivelog destination to new location 

SQL> alter system set log_archive_dest_1='LOCATION=/u01/oradata/KMDB/arch' scope = both;

System altered.

Step 3:- Verify the archivelog destination which is pointing to new location

SQL> archive log list

Database log mode              No Archive Mode

Automatic archival             Disabled

Archive destination            /u01/oradata/KMDB/arch

Oldest online log sequence     1

Current log sequence           2

Step 4:- Shutdown the database and start it in mount state

SQL> shu immediate

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL> startup mount

ORACLE instance started.

Total System Global Area  839282688 bytes

Fixed Size                  2217992 bytes

Variable Size             494929912 bytes

Database Buffers          339738624 bytes

Redo Buffers                2396160 bytes

Database mounted.

Step 5:- We need to enable archivelog mode and open the database

SQL> alter database archivelog;

Database altered.

SQL> alter database open;

Database altered.

SQL> archive log list

Database log mode              Archive Mode

Automatic archival             Enabled

Archive destination            /u01/oradata/KMDB/arch

Oldest online log sequence     1

Next log sequence to archive   2

Current log sequence           2

Disable Archivelog Mode

Step 1:- Check the archivelog mode

SQL> archive log list

Database log mode              Archive Mode

Automatic archival             Enabled

Archive destination            /u01/oradata/KMDB/arch

Oldest online log sequence     1

Next log sequence to archive   2

Current log sequence           2

Step 2:- Shutdown the database and start it in mount state

SQL> shu immediate

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL> startup mount

ORACLE instance started.

Total System Global Area  839282688 bytes

Fixed Size                  2217992 bytes

Variable Size             494929912 bytes

Database Buffers          339738624 bytes

Redo Buffers                2396160 bytes

Database mounted.

Step 3:-We need to set archivelog mode and open the database

SQL> alter database noarchivelog;

Database altered.

SQL> alter database open;

Database altered.

Step 4:- Verify archivelog mode

SQL> archive log list

Database log mode              No Archive Mode

Automatic archival             Disabled

Archive destination            /u01/oradata/KMDB/arch

Oldest online log sequence     1

Next log sequence to archive   2

Current log sequence           2

Possible Errors during activity

ORA-01126: database must be mounted in this instance and not open in any

instance

Case:- 

SQL> alter database archivelog; 

*

ERROR at line 1:

ORA-01126: database must be mounted in this instance and not open in any

instance

Cause:-

This error happens when you try to enable archivelog mode when the database is in open state 

Solution:- 

Shutdown the database and start the database in mount state