Patent ID: 8200921
Filing Date: 2012-06-12
Classification: G06F

Abstract:
1. A data synchronization method for a redundant data storage arrangement in which there are at least a primary storage entity and mirroring first and second remote storage entities in communication therewith, respectively, writes to the first and second remote storage entities being tracked via respective first and second sidefiles, the first and second storage entities having different levels of write-currency relative to each other, the method comprising: polling the second storage entity by the primary storage entity to determine an newest contiguous sequence number of the second sidefile; generating acknowledgment information based on the newest contiguous sequence number of the second sidefile; sending the acknowledgment information from the primary storage entity to the first remote storage entity; discarding at least some of the sequence numbers from the first sidefile that are equal to or older than the newest contiguous sequence number, based on the acknowledgment information; comparing sequence numbers in the first sidefile with sequence numbers in the second sidefile; and updating writes stored at the second remote storage entity based upon the comparison.