Just to be clear about a point in the linked article to MS and what others may think.
Multiple drives cannot simultaneously read/write data. It is a physical impossibility as only one bus master device (CPU, drive, ethernet, video...) can read/write RAM at a time. The commands can be sent to multiple drives, but when the data for any given command is ready (read or write), only one device can the CPU memory or I/O bus, at a time.
For hard drive access, the command phase is an insignificant part of the overall time it takes to actually complete a command.