Parallel file system and buffer management arbitration

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. For managing data for the same file distributed across multiple disk devices, a buffer manager is provided for a file system buffer pool which arbitrates use of memory resources among different system components competing for memory with buffer information for a component that said buffer manager needs for deciding how much memory to allocate among components of the system. The buffer information includes a desired memory size and current activity level. The buffer manager provides to a system component data as to how much memory has been assigned for use by that component of the system, and it schedules account resources to maximize file system throughput.