STORAGE DEVICE AND SNAPSHOT CONTROL METHOD THEREOF

摘要

Disclosed is a storage device which prevents the holding amount of data before update processing in a difference volume from increasing even if a snapshot is operated as a backup means over a long period of time. Also disclosed is a snapshot control method thereof. Specifically, by replacing a snapshot that has used data before update processing with a snapshot that uses data after update processing, an area in which the data before update processing in a difference volume is stored is released as a space area to make up for the replacement, thereby avoiding the accumulation of the data before update processing in the difference volume.