1. A method for displaying information of a network by a management server, comprising the steps of: receiving network configuration information related to topology of said network from said one or plural storage systems and a virtualization system; receiving real volume information related to a volume with which said one or plural storage systems are provided from said one or plural storage systems; receiving virtual volume information related to a virtual volume from said virtualization system; and relating and displaying said real volume information and said virtual volume information based upon said network configuration information, said network including: said one or plural storage systems; said virtualization system that provides one or plural real volumes with which said one or plural storage systems are provided to a server as a virtual volume; and said one or plural servers that access a volume with which said one or plural storage systems are provided via said virtualization system