Patent ID: 8122154

Claim:
A storage system coupled to at least one time server among a plurality of time servers through a network, comprising: a first time information holding unit that holds first time information to be used to manage an update prohibition attribute of data stored in the storage system; a second time information holding unit that holds second time information to be used to establish time synchronization with a device coupled to the network; and a time update unit that manages the first time information and the second time information, wherein the time update unit: authenticates the at least one time server, receives a third time information from the at least one time server, updates the second time information based on the third time information, compares a time indicated by the first time information with a time indicated by the third time information, and updates the first time information based on the third time information upon the successful authentication of the at least one time server and only if the time indicated by the third time information is earlier than the time indicated by the first time information; wherein the update unit receives the third time information at random intervals.