SCALABLE FILE SERVER WITH HIGHLY AVAILABLE PAIRS

The invention provides a file server system and a method for operating that system, which is easily scalable in number and type of individual components. A plurality of file servers are coupled using inter-node connectivity, such as an inter-node network, so that any one node can be accessed from any other node. Each file server includes a pair of file server nodes, each of which has a memory and each of which conducts file server operations by simultaneously writing to its own memory and to that of its twin, the pair being used to simultaneously control a set of storage elements such as disk drives. File server requests directed to particular mass storage elements are routed among file servers using an inter-node switch and processed by the file servers controlling those particular storage elements. The mass storage elements are disposed and controlled to form a redundant array, such as a RAID storage system. The inter-node network and inter-node switch are redundant, so that no single point of failure prevents access to any individual storage element. The file servers are disposed and controlled to recognize failures of any single element in the file server system and to provide access to all mass storage elements despite any such failures.