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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. Method are provided for use as a parallel file system in a shared disk environment by use of 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. For our system, tokens are used for metadata node selection and identification, and we have enhanced token modes for controlling file size, as well as smart caching of byte range tokens using file access patterns and a byte range lock algorithm using a byte range token interface. Locking techniques reduce the overhead of a token manager which is also used in the file system recovery if a computer participating in the management of shared disks becomes unavailable or failed. Synchronous and asynchronous takeover of a metadata node occurs for correction of metadata which was under modification and a new computer node to be metadata node for that file. Locks are not constantly required to allocate new blocks on behalf of a user. We have provided recoverable local shares for Quote Management. A quota server and a quote client are provided for each file system, and a quotacheck utility allows parallel environments with minimal interference to other applications which require the use of quotas.

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