The Mighty Google
For fault tolerance, Google uses GFS or distributed disk storage. Every piece of data is replicated three times. If one machine dies, a master redistributes the data to a new server. There are around 200 clusters (some with over 5 PB of disk space on 500 machines). The Big Table is used for distributed memory. The largest cells in the Big Table are 700 TB, spread over 2000 machines. MapReduce is the solution for new programming paradigms. It cuts a trillion records into a thousand parts on a thousand machines. Each machine will then load a billion records and will run the same program over these records, and then the results are recombined.
