Patent ID: 8347003

Claim:
For use with a block mode access storage protocol, a method of writing data at a given range to data stored as compressed data in at least one storage logical unit, wherein said compressed data are packed into one or more compressed sections corresponding to fixed-size portions of raw data (clusters) virtually accommodated in a virtual logical unit, the method comprising: a) determining a first cluster to be updated thereby constituting an original cluster; b) determining a serial number of an original compressed section corresponding to the original cluster; c) restoring data corresponding to said original cluster; d) calculating an offset of the data within said original cluster and updating the data within a given data range; e) compressing the updated cluster constituting an updated compressed section; and f) overwriting said original compressed section with the updated compressed section, wherein said compressed sections are divided into fixed-size compression logical units (CLU), said storage logical unit comprises a section table holding information on CLUs corresponding to said compressed sections and storage location thereof, the storing location of the data to be read is defined by referring to the section table and updating said section table after stage f).