WP-DB-Backup is a simple WordPress plugin that will take the backup of all post and database in wordpress. These are the backup list:
* wp_comments Exclude spam comments
This plugin takes a backup of WordPress databases and delivers to your email account. You can downloaded the same in the local machine. Also you can schedule automatic backups that will be delivered to your email inbox on a hourly, daily or weekly basis.
Reference link: http://wordpress.org/extend/plugins/wp-db-backup/