Computer system and snapshot data management method

摘要

A method of managing a snapshot data of a computer system provided with a computer and a storage subsystem coupled with the computer, and the computer system to which the method is applied are disclosed. The storage subsystem is provided with the duplicated first and second storage units. In the state in which they are duplicated, when a request to update data is issued to the first storage unit, the storage subsystem writes the same updated data onto the second storage unit. When an acquisition of the snapshot is requested by the computer at any time, the storage subsystem suspends the writing of the writing data for the first storage unit onto the second storage unit thereafter. When the writing of the data onto the first storage unit occurs, the computer holds the location of writing the data as differential information. When making the contents of the first storage unit and the second storage unit the same, the data written onto the first storage unit after the acquisition of the snapshot is requested is written onto the second storage unit.