Facebook ingests 15 terabytes of data a day into their 2.5 petabyte Hadoop-powered data warehouse. Hadoop is not a database nor does it need to replace any existing data systems you may have. Hadoop is a massively scalable storage and batch data processing system. It provides an integrated storage and processing fabric that scales horizontally with commodity hardware and provides fault tolerance through software. Rather than replace existing systems, Hadoop augments them by offloading the particularly difficult problem of simultaneously ingesting, processing and delivering/exporting large volumes of data so existing systems can focus on what they were designed to do: whether that be serve real time transactional data or provide interactive business intelligence.
