mong users of disparate systems. Generally, this is traced to the 1960s when many large organizations were moving to computerization and users began to have the need to share information with one another. At this point, it was common for a single organization to have multiple mainframe systems running in different geographic locations, but there was no easy way to share information among these systems even within the same organization. The challenge became even greater when individuals from different organizations, which might use different hardware, discovered that they had a need to share information with one another. The earliest solution to this situation was the development of ARPANET, a wide area network that proved to be the forerunner of the Internet (Milojicic et al, 2000).
Today's computing environment is much more complicated. Many organizations supply their employees with a discrete computerùeither a desktop or laptop computerùat their workstation; these are connected via a network. Even home computers are often networked in this way. Users on a computer at one workstation can access filesùaccording to permissions and some other variablesùphysically located on other computers that may be located across the room or across the world. In this way, information exchange remains a key reason for distributed file systems.
Another reason that distributed file systems are commonplace is resource sharing. Certainly this applies to peripherals such as printers and scanners, which can be networked and accessed by any computer on the network, but access to storage devices offers even greater benefit. Personal computers offer good ratios of price to performance, but loading the same software on hundreds or thousands of computers in an organization, and keeping that software updated, can pose significant maintenance issues. At the same time, although it can be cost prohibitive to add sufficient disk space to each perso...