Native command queueing - Definition

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Native command queueing is a technology designed to increase performance of SATA hard disks by allowing the disk firmware to internally optimise the order in which read and write commands are executed. This can result in increased performance for workloads where multiple simultaneous read/write requests are outstanding, which occurs most often in server-type applications. Normal desktop applications will show less benefit from NCQ, or potentially a performance drop in some cases due to added overhead.

For NCQ to be enabled, it must be supported and turned on in the SATA controller driver and in the hard drive itself. On some Intel chipset-based motherboards, this technology requires the enabling of the Advanced Host Controller Interface (AHCI) in the BIOS and for the installation of the Intel Application Accelerator software.

NCQ differs from some other forms of command queueing previously available on IDE and SATA in that the command reordering is done on the drive itself. This is most effective since the drive has the most knowledge of its perfomance characteristics and is able to take rotational position into account

External links

• Explanation of what NCQ does (http://www.bestpricecomputers.co.uk/reviews/NCQ/Native_Command_Queuing.htm)
• PDF white paper on NCQ from Intel and Seagate (http://www.seagate.com/content/docs/pdf/whitepaper/D2c_tech_paper_intc-stx_sata_ncq.pdf)