Importance

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Abstract

A computer system having a shared parallel disk file system running on a network for multiple computers each having their own instance of an operating system and with a protocol that makes disks appear to be locally attached to each file system. This parallel file system in a shared disk environment uses scalable directory service method improvements to caching and cache performance developments balance pools for multiple accesses. A metadata node manages file metadata, and 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 a metadata node for that file. Locks are not constantly required to allocate new blocks on behalf of a user. Hash buckets are used and each hash bucket is stored in a sparse file at an offset given as i*s, where i is the hash bucket number and s is the hash bucket size, an where a directory starts out as an empty file, where the file size increases to the size where it needs to be split by inserting records, and wherein upon a split, an additional bucket is written increasing the file size from s to 2*s upon the first split. Lookup operations are performed with a step of computing the hash value of the key being looked up, as well as a hash tree depth as log-base-2 of the file size divided by hash bucket size, and with compute steps also computed for an insert operation.

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First Claim