Storage interfaces have evolved more in the past 3 years than in the previous 20 years. In Linux, we see this happening at two different layers: (i) the user- / kernel-space I/O interface, where io_uring is bringing a low-weight, scalable I/O path; and (ii) and the host/device protocol interface, where key-values and zoned block devices are starting to emerge. Applications that want to leverage these new interfaces have to at least change their storage backends.

The de-facto way of copying data in I/O stack has been pulling it from one location followed by pushing to another. The farther the application, requiring copy, is from storage, the longer it takes for trip to be over. With copy-offload the trip gets shorter as the storage device presents an interface to do internal data-copying. This enables the host to optimize the pull-and-push method, freeing up the host CPU, RAM, and the fabric elements.