Efficient method and apparatus for access and storage of compressed data

摘要

Storage and access of compressed data via separately compressed and stored fixed size logical blocks. An original uncompressed data file is divided into fixed-size logical blocks and then separately compressed thus resulting in a compressed block of data of a generally known maximum size according to a compression ratio known in advance of the actual compression. After the uncompressed fixed-size logical block has been compressed into a maximum fixed-size logical block it is stored into space allocated to it. Furthermore, a table is built correlating the original uncompressed fixed-size logical block to the sectors allocated for each maximum fixed-size compressed logical block thus providing a mapping between the original uncompressed data file and the physical location on the storage device. Alternatively, because the compression ratio is known and because the size of the uncompressed fixed-size logical blocks is known, the resulting maximum size of the compressed logical blocks is generally known. Therefore, the maximum number of sectors allocated to each logical block is known and can thus provide the necessary mapping between uncompressed logical blocks and compressed data stored in sectors of a magnetic disk.