The entire Google backbone uses a modified Linux
It's hard to imagine just how big Google is and what scale it operates, but there is one thing that everyone should know and that it's not all that surprising. Their servers are running a custom OS based on Linux.
Google started its life in a garage back in 1998, and it's now one of the biggest companies in the world. If you also consider that most of their technology is housed in huge data centers and that Linux is the most used operating system for servers and supercomputers, it's not really surprising to find that Google is using Linux for its backbone.
It is surprising nonetheless that Google hasn't built its own operating system until now, and you can't take Chrome OS into consideration, which is based on the Linux kernel. A comprehensive article on
wired.com revealed a lot of interesting information about the search giant, including the fact that they are designing and using their own hardware, but they have yet to find something more powereful that a Linux OS for their computers.