Patent attributes
Methods, system and computer program product are provided to improve the efficiency of data transfers in a PPRC environment. Any or all of three features may be implemented, each of which reduces the number of round trips required for the exchange of handshaking, data and control information. A first feature includes disabling the “transfer ready” acknowledgment which normally occurs between a primary storage controller and a secondary storage controller. A second feature includes pre-allocating payload and data buffers in the secondary storage controller. A third feature includes packaging write control information with a write command in an extended command descriptor block (CDB). Such a step eliminated the need for a separate transmission of the write control information. The CDB is transmitted along with a data block from the primary storage controller to the secondary storage controller and placed in the respective, pre-allocated buffers. Data may also be pipelined to the secondary. By decreasing the response time for data transfers, the distance separating the primary and secondary storage controllers may be increased.
