Scalable File Serving Clusters Using Windows Storage Server Microsoft Windows Storage Server 2003 is frequently deployed as a file serving solution in small or midsize applications. I/O performance is determined by the disk drive configuration and the server hardware, typically an industry standard Intel-or AMD-based server. Many customers have viewed Windows Storage Server as an excellent small NAS solution, but have moved to larger, proprietary file server appliances when their needs expand beyond the capacity of a single Window Storage Server. This approach typically adds considerable expense and the complexity of introducing a new proprietary island system to manage. Using Melio file system, multiple Windows Storage Server 2003 file servers can be clustered into a common file system on external SAN storage. All Storage Servers have concurrent read and write access to the shared storage using Sanbolic’s clustered file system, so a request for a specific file can be processed by any of the Storage Servers accessing the shared volume on the SAN. Additional servers and additional storage arrays can be added dynamically to the cluster to expand I/O performance or storage capacity without I/O interruption while client systems continue to access data. I/O performance scales linearly as additional Windows Storage Server 2003 machines are added to the cluster. Clusters of up to 64 machines have been demonstrated, and larger clusters are possible. A large cluster can provide aggregate throughput of multiple gigabytes per second when there is sufficient performance in the backend SAN. Melio FS is a 64 bit file system, which can support very large volume and file system sizes. The 2 terabyte limit is a thing of the past. Clusters of Windows Storage Servers (available from many different OEMs on industry standard hardware) using Melio file system and backend SAN storage provide a very cost effective file serving solution that allows customers to add capacity as needed and continue to use their Windows tools to manage their file serving system. A scalable file serving cluster can be quickly and easily configured using off-the-shelf Windows Storage Servers with fibre channel or iSCSI connections to shared external storage, Microsoft DFS, and Sanbolic’s Melio file system and LaScala volume manager.