Patent ID: 8171338

Claim:
A method for transmitting an updated state of a primary computer system to a backup computer system through an intermediary computer system, wherein the backup computer system is networked to the intermediary computer system through a low bandwidth connection that does not support timely transmission of modified states of the primary computer system received by the intermediary computer system at checkpoints, the method comprising: periodically receiving, at the intermediary computer system, checkpoint information packets from the primary computer system through a high bandwidth connection, wherein each checkpoint information packet comprises updated data corresponding to memory pages of the primary computer system that have been modified since a previously received checkpoint information packet; continuously determining whether each copy of memory pages of the primary computer system stored at the intermediary computer system is a copy of a memory page that has been least recently updated by the primary computer system and has not been transmitted to the backup computer system; and transmitting updated data in each copy of each memory page determined to be a least recently updated memory page to the backup computer system through the low bandwidth connection.