For use in a storage network comprising a plurality of network elements and operable with a block mode access storage protocol, a method of operating a compression system operatively coupled to at least one computer and to one or more storage devices configured as at least one storage logical unit accommodating data compressed by the compression system, the computer, the storage devices and the compression system are configured as separate network elements. According to the method, the compression system is configured to hold a virtual logical unit, the virtual logical unit is configured to virtually represent in non-compressed form the compressed data stored in the at least one storage logical unit. The size of the virtual logical unit corresponds to an estimated size of raw data which, being compressed, would substantially amount to a size of the storage logical unit. The method includes intercepting one or more data access-related requests from the at least one computer addressed to said storage logical unit, addressing the requests to the virtual logical unit, and facilitating mapping between the compressed data and their virtual representation at the virtual logical unit.