1. An I/O device controller within an I/O device comprising: an interface to a communications component through which the I/O device controller exchanges messages and data with host computers and other remote devices; an interface to internal data storage devices; and control functionality that translates I/O requests and I/O commands received through the interface to the communications component directed to data storage units provided by the I/O device into internal I/O commands, accessing information, maintained in memory within the I/O device, about null data stored within data storage units to avoid generating and to defer internal I/O requests that result in transfer of null data, directs the internal I/O commands to the interface to internal data storage devices, receives completion messages from the interface to internal data storage devices, and returns completion messages to host computers and other remote devices through the interface to the communications component.