A system and method improve the performance of block storage over a network with asymmetric traffic by reducing the exchange of control messages between clients and servers. Before the source and the target begin exchanging data, they need to exchange control messages first to ensure the integrity of the data transfer operations. The acknowledgment messages affect the performance of backup operations when using a storage protocol such as SCSI over a reliable wide-area network protocol such as TCP/IP. SCSI protocol level and TCP/IP protocol level acknowledgment messages are combined to reduce CPU utilization at both the source and the target systems, which improves the overall system throughput and performance, and also reduces the bottleneck at the network level.