US Patent 11068364 Predictable synchronous data replication

The method, apparatus, and system disclosed herein relate to a faster and more predictable way to achieve synchronous phase from non-synchronous phase for synchronous data replication between a source volume and a destination volume. Consistency data and replication data are sent in parallel during a pre-synchronous phase to reestablish a synchronous phase of operation. Sequence identifiers and consistency sequence identifiers are used to determine whether to write consistency data to the destination volume, or to leave consistency data unwritten for blocks already updated with replication data during the process of reestablishing synchronization.