Configuration information and a system log are acquired for each of virtual servers running on an external computer, and the acquired system logs are analyzed. Relation information on the relation between the acquired configuration information and a configuration item indicating an existing snapshot, which is acquired from the same virtual server and stored, is extracted on the basis of the analysis result. Identification information for identifying the acquired configuration information is generated on the basis of the extracted relation information, and the acquired configuration information and system log are stored as a configuration item indicating a snapshot in association with the generated identification information.