Choosing an Availability Method for DFS Roots
Updated: March 28, 2003
Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2
If you plan to create DFS namespaces that must be highly available, such as those that provide access to business-critical data, the availability method you choose depends on the root type.
Stand-alone DFS roots
You ensure the availability of a stand-alone DFS root by creating it on the cluster storage of a clustered file server by using the Cluster Administrator snap-in. For more information about making stand-alone DFS roots highly available, see "Increasing Data Availability by Using Clustering" later in this chapter.
Domain-based DFS roots
You ensure the availability of domain-based DFS roots by creating multiple root targets on nonclustered file servers or on the local storage of the nodes of server clusters. (Domain-based DFS roots cannot be created on cluster storage.) All root targets must belong to the same domain. To create root targets, use the Distributed File System snap-in or the Dfsutil.exe command-line tool. (For information about choosing servers to host root targets, see "Designing a DFS Namespace" earlier in this chapter.)
To ensure the availability of domain-based DFS roots, you must have at least two domain controllers and two root targets within the domain that is hosting the root. If you have only one domain controller, and it becomes unavailable, the namespace is inaccessible. Similarly, if you have only a single root target, and the server hosting the root target is unavailable, the namespace is also unavailable.
If you plan to use more than 16 root targets, or if you have root servers in remote sites that connect to the PDC emulator master across slow links, consider enabling root scalability mode. For more information about root scalability mode, see "Reviewing DFS Size Recommendations" earlier in this chapter.
After you determine which roots need to be highly available, document your decisions. For an Excel spreadsheet to assist you in documenting the high-availability requirements of DFS roots, see "DFS Configuration Worksheet" (Sdcfsv_1.xls) on the Windows Server 2003 Deployment Kit companion CD (or see "DFS Configuration Worksheet" on the Web at http://www.microsoft.com/reskit).