Varnish HTTP Accelerator and Varnish Cache

Varnish is a web accelerator software for dynamic websites with heavy content. Unlike other software Varnish was planned to be developed as Web accelerator. We wrote many Page Speed Optimization guides, among them note worthy is the guide to W3 Total Cache Setup with CloudFlare and CDN. W3 Total Cache gives the option to setup Varnish cache. However, in this article, we will remain mainly on the theoretical part of Varnish Software.

Details on Varnish Software

Varnish is a free software, available under the BSD license. Commercial support is also offered officially. Varnish puts data in virtual memory to giving the operating system (read Linux) priority to swap out data to disk. This avoids situations in which the operating system begins to overwork with cache data as it is written by the application to disk. Varnish is a strong supporter of thread -based applications. The basic configuration is done wit Varnish Configuration Language (VCL).

Advantages of  Varnish and Role in Load Balancing

Basic health-checking of backends comes as a packed solution with the software. Previously we published in details on Load Balancing :

Load Balancing : Everything Explained With Details

Cloud Load Balancer “ Mechanism and Types of Load Balancer

The main target of Load Balancing and Web Proxy is very closer. But there are big differences. Varnish supports load balancing – both the round robin method and random director. But Varnish has negative points as well. Performance can be poor if malloc implementation is not done rightly. Configuring Varnish needs working experience that limits the number of experts to two digits for a perfectly optimized server.

This is among the reasons why a Dedicated server with proper configuration from Rackspace or Media Template costs few thousand dollars per month but those crap web hosting companies charges in two digits per month, the cost is for optimization.