Patent ID: 8005799

Claim:
An information management system including an active device and a preliminary device that are connected to each other via a communication path, the active device comprising: a first storage unit stored with data; a notifying unit attaching, when the data is stored in the first storage unit, a sequential number representing a notification number to update record information for recording an event that the data is stored, and notifying the preliminary device of the update record information via the communication path; an accumulating unit accumulating the update record information if unable to confirm completion of the notification, by the notifying unit, of the update record information via the communication path; and a unit notifying again of, when receiving a retransmission request of the update record information from the preliminary device, the update record information accumulated in the accumulating unit through the notifying unit, the preliminary device comprising: a unit monitoring the update record information of which the active device notifies and detecting, based on regularity of the sequential numbers attached to the respective pieces of update record information, missing reception of the update record information; second storage unit stored with data; a unit updating the data in the second storage unit according to the update record information of which the active device notifies; a unit making a request for, when detecting the missing reception of the update record information, retransmitting the update record information; and a unit notifying of, based on the sequential number that should be attached to the update record information with the missing of the reception, information about matching data stored in the first storage unit of the active device with data stored in the second storage unit of the preliminary device; wherein the notifying unit of the active device, when the update record information is accumulated in the accumulating unit and when receiving none of the retransmission request from the preliminary device, notifies of the update record information in a way that attaches a sequential number subsequent to the sequential number contained in the update record information accumulated in the accumulating unit to the update record information of the data newly stored in the first storage unit.