Microsoft has made numerous improvements to its Distributed File System (DFS) in Windows Server 2003 R2, particularly in the areas of replication and file availability. These improvements now make DFS a better solution than before for meeting a company's increasing storage needs, especially in branch office environments.
The two previous articles in this series looked at the way DFS makes file access across multiple file servers more transparent to an organization's users and the new DFS terminology in R2. In this article we'll look at the DFS-Namespace component.
In R2, the DFS service has been split into two separate components: DFS-Namespaces (DFS-N) and DFS-Replication (DFS-R). Splitting the DFS service into two components allows you to make a more granular decision regarding the services you deploy on your file servers. If you only use a unified namespace, you can skip installing the DFS-R component unless (and until) your environment expands to the point that it requires replication capabilities.
The DFS Namespaces feature in R2 offers the following updated capabilities:
- Target priority. If DFS detects that a particular link target or folder target is inaccessible, it will automatically route clients to another target server. In previous versions of the server operating system, if you had multiple link targets specified for a particular link, you could not specify the order in which referrals should take place. In R2, you can specify a priority list of targets that the client will be referred to.
- Client failback. In previous versions of DFS, if a client were routed past an unavailable link target to another in the list of link targets, the client would continue to use that server until the client is rebooted or until its DFS referral cache were cleared. In R2, clients can fail back to a preferred local server once its availability has been restored. However, client failback is available only for clients running Windows XP Service Pack 2 or Windows Server 2003 Service Pack 1 (including R2). Both operating systems require a hotfix that's available from Microsoft.
Note: You can configure client failback for an entire namespace, and this setting will be inherited by every folder within the namespace. You can also configure client failback for only specific folders and their folder targets.
- Delegation of authority. With DFS-Namespaces in R2, you can delegate the ability to create namespaces, as well as the ability to administer existing namespaces, by setting the necessary permissions within Active Directory (for a domain-based namespace) or in the server Registry (for a standalone namespace.) By default, you need Domain Admin rights to manage domain-based namespaces, or to be a member of the local Administrators group of the server that's hosting a standalone namespace.
About the author: Laura E. Hunter (CISSP, MCSE: Security, MCDBA, Microsoft MVP) is a senior IT specialist with the University of Pennsylvania where she provides network planning, implementation and troubleshooting services for business units and schools within the university. Hunter is a two-time recipient of the prestigious Microsoft "Most Valuable Professional" award in the area of Windows Server-Networking. She is the author of the Active Directory Field Guide (APress Publishing).
More information on this topic:
- Tip: Work around DFS limits
- Topics: Windows server management
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