Patent ID: 7318110

Claim:
A common storage system connected with first and second storage systems for exchange of information associated with instant messaging between the first and second storage systems, each of said first and second storage systems having user terminals and a server for management of the respective terminals, comprising: storage devices corresponding to each of said first and second storage systems, each of said storage devices having a synchronization controller which notifies the updated information to the other storage device, said update information including presence information, and said synchronization controller controlling the synchronization of the update information between the storage devices of said first and second storage systems; wherein said synchronization controller determines a class of said update information and notifies said updated information to said storage devices of said second storage system depending on the setting condition preset for said class of information; and wherein said setting condition is a synchronization interval time that is preset corresponding to a synchronization level, and said synchronization controller controls the timing for notifying said update information to said storage devices of said second storage system based on said synchronization interval time.