Using an rpc framework to facilitate out-of-band data transfers

A non-transitory computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method, the method comprising:

• operating a data storage system that stores sets of data blocks in extents that are located in storage devices including a sending device and a receiving device, wherein operating the data storage system includes performing the following operations on the receiving device:
• receiving, through a remote procedure call (RPC) framework, a first call to transfer an extent from the sending device to the receiving device;
• and
• in response to the first call,
• opening a port for a data connection that operates outside the RPC framework,
• making a second call, to the sending device through the RPC framework, wherein the second call asks to stream the extent to the port,
• receiving the extent from the sending device through the port,
• computing a checksum for the extent on the receiving device,
• receiving a return from the second call, from the sending device through the RPC framework, wherein the return includes a checksum for the extent computed by the sending device, and
• if the checksum computed on the receiving device matches the checksum computed on the sending device, returning the first call, through the RPC framework, to indicate the transfer operation completed successfully.

A data storage system, comprising:

• one or more storage devices including a sending device and a receiving device, wherein the one or more storage devices contain extents that store sets of data blocks;
• and
• wherein upon receiving, through a remote procedure call (RPC) framework, a first call to transfer an extent from the sending device to the receiving device, the receiving device is configured to,
• open a port for a data connection that operates outside the RPC framework,
• make a second call, to the sending device through the RPC framework, wherein the second call asks to stream the extent to the port,
• receive the extent from the sending device through the port,
• compute a checksum for the extent on the receiving device,
• receive a return from the second call, from the sending device through the RPC framework, wherein the return includes a checksum for the extent computed by the sending device, and
• if the checksum computed on the receiving device matches the checksum computed on the sending device, return the first call, through the RPC framework, to indicate the transfer operation completed successfully.