Load Balanced Cloud and High Availability Cloud are relatively less known terms. For rapidly growing websites, applications these are becoming the norm. Previously we discussed in brief about Load Balanced Cloud and how the Load Balancers work. In this article on Load Balanced Cloud and High Availability Cloud, we will use this article as a primer and introductory article, before we write in depth on these technologies in future.
Load Balanced Cloud
Take that the database is on one server – for most web software, starting from WordPress like CMS to Forum softwares – all needs a database server. Usually, the database server is located in one datacenter. Other files are distributed on different nodes – Cloud Servers. Normally when a user requests for a file, either using the GET request or through browser – like surfing this website, the first request goes to these Cloud Servers, by design the database server is nicely isolated from the public access. So, actually this Cloud Servers handle the request in various ways –
- It understand what the user is asking
- It validates whether it will allow the request
- It seeks where is the data, in most cases it seeks the data from the database server.
Then if there is no CDN, it directly serves the multiple components of the asked request.
This is why for non Load Balanced Cloud, it is always better to use three components in order to reduce the load on the main cloud servers –
- A Content Delivery Network (CDN) which will serve the static files reducing the load from the main server.
- A Database Cache which will cache everything from the database server to Cloud Servers.
- A Cache plugin, like WP Super Cache for WordPress.
All are done with the main goal – the servers will not face a huge insult if 5K visitors suddenly requests one webpage.
Load Balanced Cloud is not to replace this setup, but Load Balanced Cloud can enhance it more. In case of non Load Balanced Cloud, its the main cloud servers which are / is handling the load, but if we can configure three Load Balancers, then the load is distributed on these three load balancers first. This setup is Load Balanced Cloud and it is actually hardware optimized.
Load Balanced Cloud and High Availability Cloud
High Availability Cloud is basically a kind of multiplication of a Load Balanced Cloud, there might be five database servers, for example. High Availability Cloud is usually not suitable for our normal CMS, like WordPress MUI which wordpress.com uses actually is on a High Availability Cloud backbone.