Planning for Storage Virtualization by 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
Storage virtualization is a means to organize storage virtually instead of physically. With virtualized storage, the user sees all available storage, but is insulated from the actual physical structure and processes of storage, such as the configuration, location, and capacity of the individual devices that make up the storage system. At the network level, you can achieve virtualization by using DFS. DFS allows you to move data between servers, load balance data access among servers, and change or expand your storage configuration without impacting users.
Even if your network incorporates only a single file share, you should still build your shared storage infrastructure to use DFS. This way, as your storage needs expand, the infrastructure is already in place to support that growth. With the transparency that DFS provides, you can configure and reconfigure storage at any time with no downtime or interruption to users or applications.
The benefits of using DFS include:
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 that host 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 files to another server without having to reconfigure applications and shortcuts, and without having to reeducate 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.
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, which provides fault-tolerant data access. To ensure the availability of stand-alone DFS namespaces, you can create the root on a clustered file server.
Load sharing DFS provides a degree of load sharing by mapping a single 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.
Simplified maintenance Using multiple copies of shared folders also allows administrators to transparently perform preventive maintenance or upgrades on servers. A server that hosts one target can be taken offline without affecting users, because DFS automatically routes requests to a target that is online.
For more information about DFS, see "Designing and Deploying File Servers" in this book.