A network file system, sometimes called a distributed file system, is a method of organizing and storing files and folders in a way that involves multiple computers connected over a network. This allows many computers to access the same data and can also allow data to be spread across more than one device. The are several types of network file systems in use, each with slightly different capabilities and purposes.
Virtually any type of device used for reading or recording computer data, from hard drives to recordable compact discs, uses a file system to organize and store information. Although most share a few common features, file systems vary widely in their design, intended use, and capabilities. In most cases, a file system is confined to a single physical device such as a hard disk. Each device or disk in a computer has its own file system. A network file system takes an isolated resource, such as a hard drive inside a computer, and turns it into a shared resource available to other computers on a network.
Sharing file systems across a network can have many advantages. Files on one computer can be easily shared with other computers, and users can easily exchange information or collaborate on projects. In many cases, it is also possible to “mount” network resources so that to a user and a computer’s installed applications, the shared resource appears no different than a local resource. For example, a folder containing music or web browser bookmarks could be stored on one computer and shared with several others to keep the information in sync. In some network environments, a user’s entire home folder is shared using a network file system, allowing the user’s data to be accessible from virtually any point on the network.
There have been a variety of network file systems created since the early 1980s. Sun Microsystems® developed a protocol known as the Network File System (NFS) beginning in 1985; it is commonly used in Linux and UNIX® file servers. Microsoft® offers a product known as Distributed File System (DFS) that allows the popular Server Message Block file sharing protocol included in Windows® to be used in a network file system. The Andrew File System (AFS) aims to provide an enterprise-level network file system with new features and secure authentication through the Kerberos protocol, while the Secure Shell Filesystem (SSHFS) uses the long-lived Secure Shell protocol to accomplish a similar goal. The Google File System (GFS) and Hadoop Distributed File System (HDFS) are utilized by Google® and Yahoo!® to store vast amounts of data across thousands of individual hard disks.