Microsoft DFS provides a virtualized namespace

As an administrator, you may hear several common storage-related complaints from Windows users. One complaint is the inability to find files on networked storage. The usual situation is that users don't know or remember which server and share hosts the files. Consequently, in medium to large installations, users have to seek the help of the administrators to locate data. Another common situation is the use of drive letters. The proliferation of drive mappings can result in confusion where the U: drive of one user is different from that of another user. Or, the U: drive of one user is the S: drive of another. In some rare situations, users may even run out of drive letters.

Confused about DFS?

DFS is Distributed File Services. The Deploying File Servers is a guide on the Microsoft Web site that has a section on Distributed File Services. Deploying File Servers has other sections that deal with storage. Deploying File Servers is only a concept -- Distributed File

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Services is an implementation of logical namespace.

What is the end user benefit?

Right now, a user has to know the server name and share name to get to their data. If they don't know that or aren't told that by some admin, they may never get to the data. (The analogy I use is that we type www.yahoo.com in a browser -- we don't care about its IP address) In the same way, why should a user have to know a server name and share name? So, what DFS does is it abstracts the shares by making everything in a namespace appear as folders. Now, users are presented a logical namespace of folders by an admin. They never have to know server names and share names.

-- Sri Seshadri

Administrators have their own set of storage problems. They can't move data around from one storage device to another because this will disrupt users' knowledge of where their files are located. Administrators resort to adding larger drives on the existing servers to escape from having to move files. This affects backup and restore times as storage on servers starts to exceed 200-400 GB.

Administrators need to provide users with an intuitive way of getting to files. They want to have multiple storage devices appears as one pool to the users. They also want to consolidate file servers and move data between these servers with minimal effect on the user. In some situations, they may want data to be replicated between servers and have the users get data from the closest server hosting the share. This increases performance and provides load balancing while reducing delays in accessing heavily used folders.

Microsoft has provided such a solution since Windows NT. Using Microsoft DFS, an administrator can virtualize a set of shares and make them appear as a single pool of storage to users. In essence, the administrator creates a share of shares. Now, instead of mapping a drive to each share, the user maps a drive to the root of the DFS namespace. From the root, all other shares appear as folders under the root. Users only have to know the name of the root server and are shielded from need to remember other server and share names. This allows administrators to now move files transparent to the user.

DFS is free. A DFS based solution can provide numerous long-term benefits to users and administrators. It works well in small to large organizations and is built-in to all Windows clients.

Subsequent articles will discuss the technical aspects of DFS and how DFS can work in your environment.

About the author

Sri Seshadri is a MCSE and MCT in NT 3.51, NT 4, and W2K. For more than a decade Sri has been a consultant at DCSS specializing in Windows NT/2000 enterprise-related design, implementation, and support of large infrastructure projects. You can contact Sri at  sxseshad@dcss.com

This was first published in January 2003

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