Google's proprietary method of storing search indexes on disk. It is a distributed file system used in Google's own datacenters, and it is embedded in the Google Search Appliance, which is as a self-contained search device. It is not available as software only.
Computer Clusters and Failsafe
The Google File System (GFS) is designed to run on multiple, standard x86-based servers. It stores data in large chunks that are replicated several times throughout Google's network, and it is designed to withstand any server failing entirely. Master servers store metadata, while "Chunkservers" store the data files. See Google Search Appliance