Patent ID: 7620845
Filing Date: 2009-11-17
Classification: G06F

Abstract:
1. A distributed system comprising N processing elements where N is an integer of 4 or more, the distributed system executing a redundancy process provided at least a quorum Q of the N processing elements are communicable with each other, at least one of the N processing elements comprising: an execution state storage unit configured to store a latest execution state of the at least one processing element in a volatile memory; a resynchronization determining unit configured to determine whether to resynchronize an execution state of the at least one processing element with a latest execution state of the distributed system upon rebooting the at least one processing element, the determination being to resynchronize provided the at least one processing element can communicate with at least F+1 of the N processing elements, where F+1>=2, F=N−Q, and F>=1; and a resynchronizing unit configured to resynchronize the execution state of the at least one processing element to the latest execution state of the distributed system in accordance with the determination of the resynchronizing determining unit by: comparing sequence numbers for the at least F+1 processing elements to determine which of the at least F+1 processing elements has a highest sequence number, the processing element determined to have the highest sequence number storing the latest execution state of the distributed system, and copying the latest execution state from the processing element determined to have the highest sequence number.