Using the Windows 2000 Distributed File System

By Drew Bird | Oct 15, 2000 | Print this Page
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In Windows NT 4.0, Microsoft provided an add-on product called Distributed File System (DFS) that allowed physically separate network file resources to be grouped together and accessed as if they were a single logical structure. The product, which was a free download, failed to make a great impact with network administrators and went largely unnoticed. With Windows 2000, DFS is included with the OS and provides a number of new functions. The tool for managing the DFS structure has been improved, and wizards serve to make setup an easy task.

DFS is a service that gives administrators a way to provide users with simple access to increasingly distributed amounts of data. In this article, I will look at some of the features of DFS and how to create a DFS tree in Windows 2000.

DFS in a Heterogeneous Environment

The functionality of DFS is not just limited to Microsoft Operating systems. For instance, if the server hosting the DFS root has access to a NetWare server through client or gateway software, directories on the NetWare server can be added to the DFS tree. This is a major advantage to administrators managing data in a heterogeneous environment.[end]

DFS file structures can be accessed from any workstation that is running the DFS client software. This software is included with Windows 98, Windows NT 4.0, and Windows 2000. A downloadable client is available for systems running Windows 95. To take full advantage of the fault tolerance capabilities of DFS, the updated Active Directory Client Extensions must be installed for the respective client platforms.

What Is DFS?

DFS provides the ability to create a single logical directory tree from different areas of data. The data included in a DFS tree can be in any location accessible from the computer acting as the DFS root. In other words, the data can be on the same partition, disk, or server, or on a completely different server. As far as DFS is concerned, it makes no difference. A DFS tree appears as one contiguous directory structure, regardless of the logical or physical location of the data.

After the DFS root is created, links to directories can be added or removed to construct the single logical directory structure. The DFS tree can be navigated using standard file utilities such as Windows Explorer. Unless users are made aware of the fact that the data is being accessed from different locations, they will not realize that they are using a DFS system at all.

DFS trees can be used with both FAT and NTFS partitions. If you do use NTFS, the inclusion of a file or directory in a DFS structure has no effect on security permissions.

There are two types of DFS:

  • Stand-alone DFS--Refers to a DFS tree that is hosted on a single physical server, and is accessed by connecting to a DFS share point on that server. DFS configuration information is stored in the server's Registry. Stand-alone DFS provides no fault tolerance. If the server hosting the DFS root should go down, users will no longer be able to access their data unless they explicitly know where the data is stored.

  • Domain DFS--Provides more functionality, including features such as replication and load-balancing capabilities. Domain DFS information is stored in Active Directory. A domain member server must act as the host for the DFS tree. By storing the domain DFS configuration in Active Directory, the server-centric nature of stand-alone DFS is removed, enabling the administrator to create DFS root replicas. If a server were to go down, users would be redirected to a DFS root replica and could continue to access the DFS tree.
DFS Disk Space Reports

When a DFS share is accessed, the amount of free disk space on the drive is reported for the drive that hosts the DFS root. This amount will often differ from the amount of disk space available through different areas of the DFS structure. As an administrator, this change is easy to account for, but it can be confusing for users.

Advantages of DFS

DFS brings with it advantages for both users and administrators. All the directories and files users need to access exist in one easy-to-navigate structure. This has two effects. First, users can easily locate data, reducing the need for administrative assistance. Second, users can more easily save data in the right place, thereby increasing the effectiveness of backups and reducing related support calls. From an administrative perspective, DFS provides the ability to manage data from within one simplified structure. Other benefits include the ability to move a data structure from its original location to another drive, or even another server, without affecting the DFS structure or the users' perception of the location of the data.

Creating a DFS Tree

The initial creation of a DFS tree takes just a couple of minutes, thanks to a wizard that guides you through the necessary steps. The wizard is accessed from within the Distributed File System management utility, which can be found in the Administrative Tools menu. After starting the Management Utility, choose Action|New to launch the DFS Root Creation Wizard. After you click Next on the introduction screen, the wizard prompts you to select whether to create a stand-alone DFS root or a domain DFS root. For this example, I will create a domain DFS root.

The next two screens allow you to select first the domain, and then the server that will host the DFS root. Each server can only host one DFS root. The following screen requires that you specify the share point at which you wish to create the DFS root. You can either select an existing share by using the drop-down box, or create a new share point for the DFS root. The next screen allows you to specify a name for the DFS root, and to include a comment. Clicking Next then takes you to a summary screen, in which you can check the information that has been entered. Figure 1 shows a completed summary screen. Once the information has been checked, click Finish to create the new DFS system.

Figure 1: The completed DFS root summary screen.
Figure 1: The completed DFS root summary screen.

Adding Links

Adding new links to the DFS tree is simple. With the DFS root object selected in the management utility, right-click and choose New DFS Link. Then, simply add the path to the data you want included in the DFS tree. Repeat this procedure for each data area that you wish to add to the tree. In Figure 2, you can see the view of a DFS tree with a number of links added. The left pane shows the DFS Management Utility; the right pane shows what the tree looks like when viewed through Windows Explorer.

Figure 2: A DFS tree with added links.
Figure 2: A DFS tree with added links.

Conclusion

DFS provides a simple solution to one of network administration's most time-consuming challenges: managing data access. By creating a DFS tree, Windows 2000 administrators can manage data easily. //

Drew Bird (MCT, MCNI) is a freelance instructor and technical writer. He has been working in the IT industry for 12 years and currently lives in Kelowna, Canada. You can e-mail Drew at drewbird@netcom.ca.