Abstract: A first data mover computer services data access requests from a network client, and a second data mover computer is coupled to the first data mover computer for servicing data access requests from the first data mover computer. The first data mover computer uses a connection-oriented protocol to obtain client context information and to respond to a session setup request from the client by authenticating the client. Then the first data mover computer responds to a file system connection request from the client by forwarding the client context information and the file system connection request to the second data mover computer. Then the first data mover computer maintains a connection between the first data mover computer and the second data mover computer when the client accesses the file system and the first data mover computer passes file access requests from the client to the second data mover computer and returns responses to the file access requests from the second data mover computer to the client.

Abstract: A data storage system is constructed to rapidly respond to a physical backup request for backup of a physical storage unit such as a disk volume or cylinder. A user, however, may request backup of a logical data structure such as a file having a rather complex mapping to a number of physical storage components such as a number of disk tracks. For backup and restore of such a logical data structure, a backup agent requests an application interface routine to backup a physical storage unit that includes the logical data structure. The application interface routine issues a corresponding physical backup request to the data storage system, and creates a catalog of information about content of the physical storage unit that would be needed for restoring the logical data structure from the backup version of the physical storage unit.

Abstract: A plurality of data mover computers control access to respective file systems in data storage. A network client serviced by any of the data movers can access each of the file systems. If a data mover receives a client request for access to a file in a file system to which access is controlled by another data mover, then the data mover that received the client request sends a metadata request to the data mover that controls access to the file system. The data mover that controls access to the file system responds by placing a lock on the file and returning metadata of the file. The data mover that received the client request uses the metadata to formulate a data access command that is used to access the file data in the file system over a bypass data path that bypasses the data mover computer that controls access to the file system.

Abstract: There is a performance loss associated with servicing a pipe or stream for a connection oriented process by maintaining a connection between a server thread and a client for a series of messages. As a result of maintaining this connection, there is less balance; some threads work harder than others, causing a loss of performance. To solve this problem, a collector queue combines messages from the connection oriented process with messages from the other concurrent processes. The threads receive messages from the collector queue rather than individual pipes. Any idle thread can pick up a message from the collector queue. The collector queue keeps track of which pipe each message came from so that the reply of the server to each message is directed to the same pipe from which the message came from. Therefore the collector queue ensures thread balance and efficiency in servicing the messages. In the preferred implementation, each entry in the collector queue includes a message pointer and a pipe pointer.

Abstract: A network file server includes a first set of data processors for receiving requests from clients, and a second set of data processors for accessing read-write file systems. A respective data processor in the second set is assigned to each file system for exclusive management of read and write locks on the file system. Each data processor in the first set can authorize access to file systems directly accessed by more than one data processor in the second set. Processing of a request for access that is authorized is continued by the data processor that is assigned to manage the locks on the file system to be accessed. The exclusivity of lock management eliminates cache coherency problems, and dynamic load balancing can be used to prevent the lock management from becoming a bottleneck to performance. A preferred embodiment includes a cached disk storage subsystem linked to data mover computers.

Abstract: A video file server includes an integrated cached disk array storage subsystem and a plurality of stream server computers linking the cached disk storage system to the data network for the transfer of video data streams. The video file server further includes a controller server for applying an admission control policy to client requests and assigning stream servers to service the client requests. The stream servers include a real-time scheduler for scheduling isochronous tasks, and supports at least one industry standard network file access protocol and one file access protocol for continuous media file access. The cached disk storage subsystem is responsive to video prefetch commands, and the data specified for a prefetch command for a process are retained in an allocated portion of the cache memory from the time that the cached disk storage subsystem has responded to the prefetch command to the time that the cached disk storage subsystem responds to a fetch command specifying the data for the process.

Abstract: For network file access, a plurality of data mover computers are linked to a cached disk array. Read-write files stored in the cached disk array are accessible to network clients through more than one of the data mover computers so that the data mover computers are not a bottleneck to file access. The cached disk array stores a network file directory including file locking information, and the data mover computers each have file system software that accesses the network file directory for shared read-write file access. The data mover computers perform the file system tasks such as managing the file directory for mapping of file names to logical blocks and for locking and unlocking of the files in order to minimize loading on the cached disk array. Therefore, the network file server need not use any particular one of the data mover computers to serve as a control point for read-write file access. Instead, file system software for managing the file directory is replicated in each data mover computer.

Abstract: A network file server includes an integrated cached disk array and a plurality of data mover computers linking the cached disk array to the data network for file access. Each data mover computer maintains a local cache of file directory information including locking information of locked files that are accessible through the data mover. A cache consistency scheme ensures that shared locking information is consistent in the local caches. In a preferred embodiment, the cache consistency scheme uses an internal data link to pass messages between the data movers. The file directory information in the local cache includes information mapping file names to a list of logical blocks for each file name, file attributes that affect data access, and locking information down to a block level of granularity.

Abstract: A video file server includes an integrated cached disk array storage subsystem and a plurality of stream server computers linking the cached disk storage subsystem to a data network for the transfer of video data streams. The video file server further includes a server controller for applying an admission control policy to client requests and assigning stream servers to service the client requests. The stream servers include a real-time scheduler for scheduling isochronous tasks, and supports at least one industry standard network file access protocol and one file access protocol for continuous media file access. The cached disk storage subsystem is responsive to video prefetch commands, and the data specified for a prefetch command for a process are retained in an allocated portion of the cache memory from the time that the cached disk storage subsystem has responded to the prefetch command to the time that the cached disk storage subsystem responds to a fetch command specifying the data for the process.

Abstract: A conventional network file server has a file system that permits file attributes and file data to be written in any order. The conventional network file server may also support an asynchronous write protocol, in which file attributes and file data need not be written to disk storage until a client sends a commit request. This asynchronous write protocol has a data security problem if the attributes are written before the data and the server crashes before completing the writing of the data to disk storage. This security problem is solved by adding a file system cache and following a protocol that writes the attributes to storage after writing the data to storage. For example, the attributes and data are stored in the file system cache and are not written down to storage until receipt of a commit request. When the commit request is received, the data is sent first from the file system cache to storage. Then the attributes are sent from the file system cache to storage.

Abstract: A video file server includes an integrated cached disk array storage subsystem and a plurality of stream server computers linking the cached disk array to a data network for the transfer of video data streams. The video file server further includes a controller server for applying an admission control policy to client requests and assigning stream servers to service the client requests. The stream servers include a real-time scheduler for scheduling isochronous tasks, and supports at least one industry standard network file access protocol and one file access protocol for continuous media file access. The cached disk storage subsystem is responsive to video prefetch commands, and the data specified for a prefetch command for a process are retained in an allocated portion of the cache memory from the time that the cached disk storage subsystem has responded to the prefetch command to the time that the cached disk storage subsystem responds to a fetch command specifying the data for the process.

Abstract: A video file server includes an integrated cached disk array storage subsystem and a plurality of stream server computers linking the cached disk storage subsystem to the data network for the transfer of video data streams. The video file server further includes a controller server for applying an admission control policy to client requests and assigning stream servers to service the client requests. The stream servers include a real-time scheduler for scheduling isochronous tasks, and supports at least one industry standard network file access protocol and one file access protocol for continuous media file access. The cached disk storage subsystem is responsive to video prefetch commands, and the data specified for a prefetch command for a process are retained in an allocated portion of the cache memory from the time that the cached disk storage subsystem has responded to the prefetch command to the time that the cached disk storage subsystem responds to a fetch command specifying the data for the process.

Abstract: A scheduler with admissions control in a continuous media file server is presented. The scheduler supports multiple classes of tasks with diverse performance requirements. The scheduler is based on a combination of rate-monotonic and weighted round-robin scheduling schemes. Scheduling is accomplished in a hierarchical manner. Isochronous tasks have the highest priority and are scheduled first followed by real-time and general-purpose tasks. Isochronous tasks run periodically and are invoked by a timer interrupt set for each task. After scheduling the isochronous tasks, the scheduler alternates between the real-time tasks and the general-purpose tasks using a weighted round-robin scheme.