In this blog post, we’ll cover the basics of the Distributed File System (DFS) in Windows Server 2008, which offers users simplified access to a set of file shares and helps administrators easily maintain the file server infrastructure behind those file shares, including options for load sharing, replication and site awareness.
Many File Servers and File Shares
It’s a common scenario. Over time, a company ends up with a large number of file servers that were created at different times and by different teams. The users are left to figure out where their files are stored, mapping many drives to file shares and learning complex UNC paths like \\server23\ffiles and \\finance.asia.company.com\spreadsheets and even something like \\10.1.23.45\scratch. To complicate things further, when an old file server is replaced, paths are broken and mapped drives stop working. It can be challenging.
You also probably heard the proposition to invest in a complex project to consolidate everything into a large file server or NAS appliance. While those projects will solve the problem for a while, you will need to spend a lot of resources to move the data around and fix users’ mapped drives and paths. All that to have that new server eventually become too small and need replacing again. Or you will need many of those larger servers, starting the cycle over.
It turns out it doesn’t have to be that way. Windows Server already provides a way to manage a large set of file shares as a consolidated list, under common namespaces. From your users’ perspective, each namespace looks like a single file share with many folders. From an administrators’ perspective, you can easily add more file servers or consolidate existing file servers without complex “forklift” migrations. And those are just a few of the benefits of DFS.
Adding the DFS Services
DFS Services are available on all currently supported versions of Windows Server, but there are significant improvements in the Windows Server 2008 editions. The DFS namespace client is available for all currently supported versions of Windows, both client and server. Domain-based DFS namespaces require the use of Active Directory.
To add the DFS Services to Windows Server 2008, you will use the Server Manager tool. First, you need to expand the “Roles” item on the tree to make sure that the File Service role is installed. Then you will right-click on “File Services” and click on option to “Add Role Services”. That’s where you you will find the option to add DFS:
Another way to add the DFS Services is using the ServerManagerCmd.EXE command line tool. You can also use ServerManagerCmd to make sure that the right role and role services are installed. Here’s a sample command line:
C:\>servermanagercmd -query | find "[FS" [X] File Server [FS-FileServer] [X] Distributed File System [FS-DFS] [X] DFS Namespaces [FS-DFS-Namespace] [X] DFS Replication [FS-DFS-Replication] [ ] File Server Resource Manager [FS-Resource-Manager] [X] Services for Network File System [FS-NFS-Services] [ ] Windows Search Service [FS-Search-Service] [ ] Windows Server 2003 File Services [FS-Win2003-Services] [ ] File Replication Service [FS-Replication] [ ] Indexing Service [FS-Indexing-Service] C:\>
A DFS namespace is basically a place where you will have links to all your file shares. From an administrator point of view, you should think of it as a folder structure where you keep the list of target file shares. Your users will see it as a single share with many folders and they will have no idea that they are navigating across a set of servers to get to the subfolders and files.
When configuring DFS, you have a choice of using a domain-based or a stand-alone namespace. If you already have Active Directory deployed, you should consider using a domain-based namespace. If you’re not using Active Directory, your only choice is a stand-alone one.
The main advantage of the domain-based namespaces is that your configuration will be stored in Active Directory and you won’t have to rely on a single server to provide the namespace information to your clients. The path users refer to uses the name of the domain and it will not need to change because your namespace server name changed (only if you change your domain name). With a stand-alone DFS, that server name becomes part of the main path to the namespace.
There are also two domain-based DFS modes: Windows Server 2008 mode and Windows Server 2000 mode. Windows Server 2008 mode (which requires Windows Server 2003 forest functional level, Windows Server 2008 domain functional level and Windows Server 2008 running on all namespace servers) includes support for more than 5,000 folders with targets per namespace and access-based enumeration.