The abstract of the patent published by the U.S. Patent and Trademark Office states: ”Systems and methods for maintaining data consistency across mirrored storage nodes. Data consistency may be maintained in networked storage environments using a timestamp of an I/O in the primary and secondary servers, (also referred to as nodes) in synchronous replication to re-synchronize the data efficiently, without much performance drop and while reducing the memory footprint. According to an aspect presented herein, data consistency is maintained in a mirror node by timestamping the I/O for a volume's logical territory in both the primary and secondary nodes. The timestamp acts as a watermark. Thus, whenever a disaster or failure occurs, the watermark point determines the re-synchronization point.“
The patent application was filed on April 18, 2012 (13/449,567).