Reviewing the Benefits of Using DFS
Updated: March 28, 2003
Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2
When you evaluate DFS for your organization, it is helpful to understand the benefits that your organization can gain after designing and implementing a DFS namespace. The following list describes the benefits of using DFS:
Unified namespace A DFS namespace links together shared folders on different servers to create a hierarchical structure that behaves like a single high-capacity hard disk. Users can navigate the logical namespace without having to know the physical server names or shared folders hosting the data.
Location transparency DFS simplifies migrating data from one file server to another. Because users do not need to know the name of each physical server or shared folder that contains the data, you can physically move data to another server without having to reconfigure applications and shortcuts, and without having to re-educate users about where they can find their data.
Storage scalability You can deploy additional or higher-performance file servers and present the storage on the new servers as new folders within an existing namespace.
Namespace scalability Servers running Windows Server 2003, Enterprise Edition or Windows Server 2003, Datacenter Edition can host multiple domain-based DFS roots and stand-alone DFS roots. This feature improves the scalability of DFS, enabling you to build many large namespaces without having to add file servers to host the roots.
Increased availability of file server data When multiple servers running Windows Server 2003 host a domain-based DFS root, clients are redirected to the next available root server if any of these servers fail, providing fault-tolerant data access. To ensure the availability of stand-alone DFS namespaces, you can create the root on a clustered file server.
Alternate site selection based on cost By default, if a target in the same site as the users fails, or if no same-site target exists, DFS refers clients to a random target. If you configure the optional site costing feature, DFS can use the site information in Active Directory to locate an alternate target that has the lowest-cost network connection as defined by the administrator in the Active Directory Sites and Services snap-in. After site costing is enabled, clients can access data on DFS targets over the optimum network connection.
Load sharing DFS provides a degree of load sharing by mapping a given logical name to shared folders on multiple file servers. For example, suppose that \\Company\StockInfo is a heavily used shared folder. By using DFS, you can associate this location with multiple shared folders on different servers, even if the servers are located in different sites.
Intelligent client caching When a user requests access to a target that is a part of a DFS namespace, a referral containing the target’s information is cached on the client. The next time the client requires access to that portion of the namespace, the client uses the cached referral instead of obtaining a new referral, and connects directly to one of the target computers. For more information about client caching in DFS, see the Windows Security Collection of the Windows Server 2003 Technical Reference (or see the Windows Security Collection on the Web at http://www.microsoft.com/reskit).
Support for offline folders If your clients are running Microsoft® Windows® XP or Windows Server 2003, you can make DFS link targets available offline by using the Offline Files feature. You can also use this feature to automatically cache programs so that users can run the programs locally instead of from the server. Using this feature for link targets that host applications can reduce network traffic and improve server scalability.
Simplified maintenance If a link has multiple link targets, administrators can perform preventive maintenance, repairs, or upgrades on servers by disabling referrals to specific link targets. While the referral to the link target is disabled, DFS automatically routes new requests to the remaining link targets that are online.
Dynamic site discovery DFS now supports dynamic site discovery. In Windows 2000, DFS maintained static site information. After the site information for a particular network resource was known, DFS used that information indefinitely, regardless of any changes in the site information of the resource. In Windows Server 2003, when you move a resource from one site to another, the information used by DFS converges to the new site information within 25 hours.
Security integration You do not need to configure additional security for DFS namespaces, because file and folder access is enforced by existing NTFS and share permissions on each link target. For example, a user navigating a DFS namespace is permitted to access only the files or folders for which he or she has appropriate NTFS or share permissions. If you use FRS to replicate content among multiple targets, FRS also replicates access control lists (ACLs) for each file and folder. For more information about DFS and FRS security, see "Planning DFS and FRS Security" later in this chapter.