How can we configure the Master slave concept in Drupal 7? I have one large scale website and hosted on AWS. I want to enable Master-Slave concept on it. How can it be possible to configure the same?
Yes, Drupal supports master/slave style database replication.
Note: master/slave replication configuration is done at the database server level. Drupal simply utilizes the replicated databases by using the slave server when one database isn't available, or for specific 'slave' marked queries ( see db_query &quot;target&quot; option ).
See the fully commented default.settings.php for Drupal configuration details.

For each database, you may optionally specify multiple &quot;target&quot;
databases. A target database allows Drupal to try to send certain
queries to a different database if it can but fall back to the default
connection if not. That is useful for master/slave replication, as
Drupal may try to connect to a slave server when appropriate and if
one is not available will simply fall back to the single master
server.
The general format for the $databases array is as follows:

$databases['default']['default'] = $info_array;
$databases['default']['slave'][] = $info_array;
$databases['default']['slave'][] = $info_array;
$databases['extra']['default'] = $info_array;