1. A storage system comprising: at least one processor; a processor memory; an input-output controller; and a directly-addressable storage device having volatile memory and non-volatile memory; wherein the input-output controller generates a plurality of write commands in conjunction with storage of data in the storage system, the write commands including at least a first write command comprising the data and a second write command comprising one or more interrupts; if an address of a given one of the write commands falls within a specified data group window, the data is written to the processor memory and the write command is copied to the directly-addressable storage device so as to cause the data to also be written to the volatile memory of that storage device; if the address of the given write command does not fall within the specified data group window and does not fall within a specified interrupt group window, the data is written to the processor memory but the write command is not copied to the directly-addressable storage device; if the address of the given write command falls within the specified interrupt group window, the write command is copied to the directly-addressable storage device so as to provide at least one of the one or more interrupts to that storage device; wherein the directly-addressable storage device responds to receipt of the interrupt by writing data from the volatile memory to the non-volatile memory and generating a corresponding additional interrupt to the processor.