To scale its services, the company has developed many systems, such as MapReduce and Google File System, that have since been made open source by Yahoo and worked into the popular Hadoop data-analytics framework.
However, behind the scenes, the company is fighting a constant battle against the twin demons of cascading failovers and the increasingly challenging levels of complexity that massively scaled services bring.
Urs Hölzle was Google's first vice president of engineering. Before joining Google he worked on high-performance implementations of object-orientated languages, contributed to Darpa's national compiler infrastructure project, and developed compilers for Smalltalk and Java.
According to Hölzle, "at scale, everything breaks", and Google must walk a tightrope between increasing the scaling of its systems while avoiding cascading failovers, such as the outage that affected Gmail in March this year.