The Google Web Server - a custom server used only by Google itself - was originally built from open-source Apache code, according to a former Google employee.
However, over the past several years, the server has been so heavily modified that it now bears little resemblance to the ubiquitous Apache server. It is so tightly tied to Google's famously distributed internal infrastructure, the ex-employee says, it could not be used for serving sites outside of the company.
The Google Web Server is known as GWS - pronounced "gwiss" - inside the Mountain View Chocolate Factory. According to the ex-employee, it's chock full of custom I/O handles meant to interface with Google-specific remote procedure calls.
Google's private infrastructure - sometimes referred as "The Google Network" - spans nearly 40 data centers across the globe, and it's pieced together with myriad custom-built and proprietary tools, including a distributed file system dubbed GFS; a distributed number-crunching platform known as MapReduce; and a new platform known as Spanner, designed to automatically move and replicate loads between the company's mega data centers.
The latest survey data from the web-server-tracking UK research outfit Netcraft shows that even though GWS is only used inside of Google, it's now hosting nearly 13 per cent of all active websites. That's 11 million sites that are regularly updated with new content. This includes not only sites run solely by Google, but also sites the company operates on behalf of third parties via services like Blogger, Google Sites, and Google App Engine.
According to Netcraft, Apache runs 44 million active sites, and Microsoft servers run nearly 14 million.
In a 2007 web post, conspicuous Googler Matt Cutts indicated that GWS was not based on Apache. "That's not correct," he wrote. "I believe GWS is a custom web server, not a modified version of Apache." But this hardly seems authoritative.
For Java applications, Mountain View uses another custom server, which is apparently known as GFE. That's Google Front End - not girlfriend experience. GFE is mentioned in the same 2003 blog post where Cutts comments on Google Web Server. According to the ex-employee, the word inside Google is that this custom Java server "blows Tomcat out of the water."
Google has not responded to our requests for comment on GWS or GFE. ®