Abstract: A network file system includes at least one unmodified client and at least one unmodified physical file server (PFS). Each PFS has at least one file that is identified by an associated physical file handle (PFH). The network file system includes virtual file servers (VFSs) in a data path between the client(s) and the PFS(s). The network file system also includes a virtualized name space that is mapped to the PFS(s) and is provided to the client(s) by the VFS(s). The network file system further includes a virtualized ID space that is established in response to a request from a client. Within the ID space, each file is identified by a physical file handle (PFH) on a PFS. The PFH and PFS pair are mapped to provide a virtual file handle (VFH), and the map of the VFHs is allocated among the VFSs.

Abstract: A method of providing protocol virtualization for a network file system. In particular, at least one virtual file server is established in the data path between the clients and the physical file systems. The virtual file server presents a virtualized name space and a virtualized ID space to the clients, the virtualized name and ID space representing the physical files on the physical file servers. To the clients, the virtual file server appears to be file server. To the physical file servers, the virtual file server appears to be a client. Junction directories permit the virtual file servers to combine physically separate directories to appear as one, and permit migration of objects between the physical file servers without perception by the clients.

Abstract: A method (and system) of transferring data of multimedia objects from servers to clients using memory in video-on-demand clusters, includes dividing multimedia objects into segments and independently serving and caching the segments on a plurality of servers, retrieving the segments from the servers, directing the client to the server that is responsible for serving the at least one of the segments using a redirection algorithm, and predicting a likely sequence of segments that will be requested by the client and prefetching data from a next segment in the likely sequence of segments and loading the next segment into memory within one of the plurality of servers.