Abstract: A computer system having a shared disk file system running on on multiple computers each having their own instance of an operating system and being coupled for parallel data sharing access to files residing on network attached shared disks. Methods are provided for use as a parallel file system in a shared disk environment by use of a scalable directory service for the system with a stable cursor, a segmented allocation map. Dynamic prefetch and cached balance pools for multiple accesses improve the system. Extended file attributes are used for implementation of Access Control Lists in a parallel file system. Improvements to caching and cache performance developments balance pools for multiple accesses. A metadata node manages file metadata for parallel read and write actions.

Abstract: A computer system having a shared disk file system running on multiple computers each having their own instance of an operating system and being coupled for parallel data sharing access to files residing on network attached shared disks. Methods are provided for use as a parallel file system in a shared disk environment by use of a scalable directory service for the system with a stable cursor, and a segmented allocation map. Dynamic prefetch and cached balance pools for multiple accesses improve the system. Extended file attributes are used for implementation of Access Control Lists in a parallel file system. Improvements to caching and cache performance developments balance pools for multiple accesses. A metadata node manages file metadata for parallel read and write actions.

Abstract: An improved method for supporting an empirical measurement of the data bandwidth that one or more computer disks can continuously sustain while reading data. In a computer system having predetermined workload requirements and disk storage for storing an allocation table including entries for meta blocks and data blocks, a method for supporting a dynamic measurement of the read bandwidth of a disk, includes the steps of: creating an alternate allocation table that ignores the existing content of the disk; creating meta blocks for a phantom file by allocating the meta blocks from the allocation table; allocating data blocks for the phantom file from the alternate allocation table; and writing only meta blocks to the disk, but not actual data blocks. Since the actual data blocks are by far the largest component of the files, phantom files require only a very small number of disk blocks, and can be written very quickly.

Abstract: A multimedia datastreaming system includes one of a plurality of differing pre-existing file systems each supporting a set of zero copy function interfaces. A method is provided for supporting the zero copy function of a datastream file with the pre-existing file system. A general purpose file system interface is established to the pre-existing file systems. The general purpose file system interface is then invoked to affect zero copy transfer of the datastream from a producer module to a consumer module. An initial prefetch of data associated with the datastream file is initiated in response to an I/O command issued from a multimedia file system daemon, such prefetch being from mass storage to a buffer in shared memory in an interrupt context.