What is NCQ (Native Command Queueing) and Why do we want it?
Ans: This explaination is an excerpt from our Nforce 4 Tech Preview. One area that SCSI had over both parallel and SATA drives was Native Command Queuing (NCQ). Traditionally hard disks on the consumer desktop side process disk requests in a linear fashion. This can potentially be a very bad thing and to understand why, there has to be a basic understanding of the physical structure of a hard disk. Hard disks are made up of platters or disks, much like a compact disk. Each platter is divided into tracks which are concentric circles, tracks are divided into sectors. Each platter is read by one or more heads. Seeking data is fastest when the data resides on the same track. Moving between tracks is time consuming. Consider the case where there are three pieces of data, one on the outermost track, one on the inner most track and one on the outmost track. In a traditional hard disk, the data on the outer track would be read first, then the data on in the inner track second, and finally the
