Storage system, storage controller and data compression method

One or more storage controllers for storing file data to be compressed sent from a host system, comprising:

• a statistical information management unit for managing a throughput value decided based on statistical information of previously compressed file data as a system performance value;
• a mode setting unit for setting a compression mode of either a system performance priority mode that terminates compression of said file data and gives priority to system performance or a compression priority mode that gives priority to compression of said file data based on a comparison between a system performance target value preset as a target value and said system performance value;
• a concordance detection unit for detecting a location of concordance between an input data sequence obtained by encrypting said file data, and a dictionary data sequence as a previously encrypted input data sequence;
• and
• a termination controller for controlling termination of compression of said file data based on a comparison between said compression mode and said location of concordance.

A data compression method of a storage system comprising one or more storage controllers for storing file data to be compressed sent from a host system,

• wherein said one or more storage controllers comprise:
• a statistical information management step of managing a throughput value decided based on statistical information of previously compressed file data as a system performance value;
• a mode setting step of setting a compression mode of either a system performance priority mode that terminates compression of said file data and gives priority to system performance or a compression priority mode that gives priority to compression of said file data based on a comparison between a system performance target value preset as a target value and said system performance value;
• and
• a compression control step of compressing said file data based on said compression mode set at said mode setting step.