Abstract: A special-purpose file system is provided which includes a combination of services and features which improve the performance of applications employing caches, such as caching web proxies. This file system also provides a file system cache which can be used as a general high-performance file system cache for file systems which need a cache. The services and features include collocating files together on a disk; keeping file meta-data in memory; compressing file names to hash values for reference; using a flat naming scheme for files; providing background daemons that pack files into clusters and clean disk and main memory space; and implementing a user-level library. The file system reduces access to related disk files, eliminates disk operations that are needed to maintain directory and meta-data information, and avoids multiple buffering of file data, and saves and efficiently manages disk and main memory space.

Abstract: A data storage system includes a computer coupled to a non-volatile storage, such as a disk drive, through an interconnect. The computer may include a block cache for storing cached copies of data blocks, and a hash table that stores hash values corresponding to the data blocks. Prior to writing back a modified cache block to the non-volatile storage, a log recorder of the computer stores an updated hash value corresponding to the modified cache block within a write-ahead hash log, which may also be also contained in non-volatile storage. In one particular implementation, the log recorder may create a log record including an updated hash value and an address corresponding to a modified cache block.