Failover Hosting

Failover Hosting

Wednesday, July 20th, 2011

This is an article explaining the exact functioning of Failover Hosting Architecture. Most of you reading web hosting articles should have come across the term failover hosting solutions. You must be wondering, what exactly the failover hosting and How does the failover hosting works ?

What is Failover Hosting ?
Failover Hosting also referred as failover cluster, is a kind of popular service that ensures 100% network uptime and redundancy. Basically, it is used where round the clock availability and redundancy is required for the applications, websites and services. In most of the organizations, this architecture is used for ensuring the databases redundancy.

How Does the Failover Hosting Works ?
Basically, the failover architecture has the capability of switching automatically to a secondary server also called as a Slave server in case if the primary server (ie. Master server) goes down. Usually, to make sure the master server is running perfectly, a monitoring script is used on the slave server. The monitoring system keeps an eye on the master server and its configured services. Whenever a configured services fails on the master server, the failover architecture starts functioning and all the user and application requests are routed to the next slave server automatically. All this process is done within a fraction of a second and the requests are fulfilled without having any downtime and without the need of human intervention.

Using the Rsync scripts any data and file update or change on the master server is synced on the slave server. If required a shared storage can also be provided for MySQL databases.

Most of the hosting providers normally offer the failover capability in the servers by configuring some specific services, systems or networks that requires continuous availability and greater reliability. The functioning of the failover architecture depends on the “monitoring script” which is used to check the status of the master server. The script helps to detect a failover in a cluster of servers. However, there are many monitoring software’s available such as “Heartbeat”, but here at eUKhost we use a custom monitoring script.

Usually, the monitoring script located on the slave server sends a “Ping” and checks the “Apache” status of the master server, and indicates that the the master server is live and the services are running perfectly on it. The slave server will not initiate its systems until the master server fails working properly. Many of the hosting providers uses more than two servers in a cluster such as spare or a redundant server having spare components in case if it requires to “hot” switching.

If the “Ping” doesn’t get any reply, the custom script checks the “Apache” status of the master server and if the Apache is running properly the IPs will not switch. However, in case, if the “Ping” and “Apache” both are down, in that case the IP addresses of master server automatically gets routed to the slave server within a fraction of a second and all the websites and applications starts resolving from the slave server.

Nowadays, there are many advanced systems has been developed having the ability to SMS or email a message on a particular web hosting technician’s email address.

This is one of the best way to ensure the 100% uptime guarantee and high availability. If you are in search of Failover Hosting solution, all you need to do is, sign-up for two dedicated servers placed at two different data centers and ask your hosting provider to make them into a Failover solution according to your requirements.

Article by Mac Wilson at

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