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DFS (Distributed File System)
Note: Many topics at this site are reduced versions of the text in "The Encyclopedia of Networking and Telecommunications." Search results will not be as extensive as a search of the book's CD-ROM.
There are two file systems that take the acronym "DFS:" The Open Group's DFS and Microsoft's DFS. While they are both distributed file systems, they have little in common.
The Open Group DFS (Distributed File System)
DFS (Distributed File System) from The Open Group is a version of the AFS (Andrew File System) that is included with The Open Group's DCE (Distributed Computing Environment). Transarc is responsible for DFS. Its Web site is http://www.transarc.com. Refer to "AFS (Andrew File System)" for more information. Also refer to "Open Group" and "DCE (Distributed Computing Environment)."
Microsoft DFS (Distributed File System)
Microsoft DFS is designed to make it easier to access files on networks. It provides a way to unite files on different computers under a single name space. To the user, files appear as if they are in one location, rather than on separate computers. A hierarchical tree provides a view of these files, and users can "drill down" through the tree to find just the information they are looking for.
The user does not need to know or care about the physical location of the file, only where it is located in the hierarchical view. That means that users no longer search for files by opening file servers and disk drives, and looking through a separate directory structure on each. Instead, users look through a logical directory that places shared information in a place that makes more sense to users and administrators alike. With DFS, an administrator does up-front work to logically organize information, so users don't have trouble finding it later on.
As an analogy, think of a city library system in which the book catalog at each library lists all the books available at libraries throughout the city. You can order any book and it will be delivered from its current location. The important point is that there is one library catalog system that provides a list of all the books available, no matter what their physical location. DFS provides a single "catalog" view of files on your network, no matter where those files are located.
Some of the benefits of DFS are outlined here:
DFS fits into an organization's Internet and intranet strategy. The Web page of individual departments or even users can be included within the directory tree. DFS can also hold HTML links; so, if linked pages are moved to a different physical location, all links pointing to the pages will not have to be reconfigured.
A DFS volume starts out by being hosted by a specific computer. There may be many individual DFS volumes available on a network, and each will have its own distinct name. Windows NT/Windows 2000 servers are currently the only systems that can host DFS volumes. An organization might have a master DFS volume that contains links to other DFS volumes at the department or division level. Another volume might tie together shares that are common in each department, such as public documents.
In the DFS volume name shown here, the hosting computer name is Server_Name:
\\Server_Name\DFS Share Name\path\name
Like a local file system, a DFS volume has a root that is its starting point. This is represented by DFS_Share_Name. The reference to path\name can be any valid pathname.
Figure D-20 illustrates how links work. Three departments-Marketing, Engineering, and Research-have set up their own name spaces to fit their own needs. The corporate DFS volume links into specific parts of these shares as needed to provide corporate users with information from other locations in the organization. When a link is accessed, the junction between two different DFS volumes is crossed and the server that provides the DFS root changes. This is transparent to the user, however.
Figure 20: See book
Copyright (c) 2001 Tom Sheldon and Big Sur Multimedia.