Google's system can be defined as direct-attached storage (DAS), where, oddly enough, storage is attached directly to a computer. The vast majority of big storage networks in use are network-attached (NAS) - where a data server on a network provides storage accessed via the network - or storage area network (SAN) - a high-speed subnetwork of shared storage devices.
Came across this article in a trade paper this week, but they didn't put it on their site with today's update. Found the original (3 week old) article, though... It's interesting but, of course, not as in-depth as we would like.