Below are the steps for enabling archive mode or wal archiving in postgres.

STEPS TO ENABLE ARCHIVE MODE IN POSTGRES:

1. Check archive setting in the postgres config file:

postgres=#select name,setting from pg_settings where name like 'archive%' ;
          name           |  setting
-------------------------+------------
 archive_cleanup_command |
 archive_command         | (disabled)
 archive_mode            | off    --- >>>
 archive_timeout         | 0
(4 rows)

postgres=#show wal_level
 wal_level
-----------
minimal
(1 row)

If wal_le

2. Now alter below parameters:

Alternatively you can change below parameter directly in the postgres.conf file:

postgres=#alter system set archive_mode=on;
ALTER SYSTEM

postgres=#alter system set archive_command='test ! -f /var/lib/edb/as12/archive/%f && cp %p /var/lib/edb/as12/archive/%f';
ALTER SYSTEM

postgres=#alter system set wal_level=replica;
ALTER SYSTEM

3. Now restart the postgres instance:

[root@]#systemctl stop edb-as-12
[root@]#systemctl start edb-as-12

-- ALTERNATIVELY YOU CAN USE PG_CTL COMMAND:

export PGDATA=/var/lib/edb/as12/data
pg_ctl stop
pg_ctl start

4. Now check archive mode:

postgres=#select name,setting from pg_settings where name like 'archive%';
          name           |                                   setting
-------------------------+------------------------------------------------------------------------------
 archive_cleanup_command |
 archive_command         | test ! -f /var/lib/edb/as12/archive/%f && cp %p /var/lib/edb/as12/archive/%f
 archive_mode            | on
 archive_timeout         | 0
(4 rows)

postgres=#show wal_level;
 wal_level
-----------
replica
(1 row)

5. Do manual log switch and check whether archive is generating or not:

postgres=#select pg_switch_wal();
 pg_switch_wal
---------------
 0/1D392648
(1 row)

postgres=#select pg_switch_wal();
 pg_switch_wal
---------------
 0/1E000000
(1 row)

[enterprisedb@localhost archive]$ pwd
/var/lib/edb/as12/archive

-rw-------. 1 enterprisedb enterprisedb 16777216 Oct 20 19:44 00000001000000000000001C
-rw-------. 1 enterprisedb enterprisedb 16777216 Oct 20 19:56 00000001000000000000001D

STEPS TO DISABLE ARCHIVE MODE:

1. Set archive_mode to off:

postgres=#alter system set archive_mode=off;
ALTER SYSTEM

2. Now restart the postgres instance:

[root@]#systemctl stop postgresql-9.5.service
[root@]#systemctl start postgresql-9.5.service
[root@]#systemctl restart postgresql-9.5.service
[root@]#systemctl status postgresql-9.5.service
[root@]#systemctl reload postgresql-9.5.service

3. Check archive mode:

postgres=#select name,setting from pg_settings where name like 'archive%';
          name           |                                   setting
-------------------------+------------------------------------------------------------------------------
 archive_cleanup_command |
 archive_command         | test ! -f /var/lib/edb/as12/archive/%f && cp %p /var/lib/edb/as12/archive/%f
 archive_mode            | off
 archive_timeout         | 0
(4 rows)