Native Command Queuing

Native Command Queuing (NCQ) is a command protocol in Serial ATA that can be implemented only on native Serial ATA hard drives. It allows multiple commands to be outstanding within a drive at the same time. Drives that support NCQ have an internal queue where outstanding commands can be dynamically rescheduled or re-ordered, along with the necessary tracking mechanisms for outstanding and completed portions of the workload. NCQ also has a mechanism that allows the host to issue additional commands to the drive while the drive is seeking data for another command.

NCQ allows the drive to set up the direct memory access (DMA) operation for a data transfer without host software intervention. This is also called first-party DMA – it means that the device is capable of complex sequences of operations without CPU intervention. The drive itself knows the current angular and rotational position of the drive head. The drive then selects the next data transfer to minimize both seek and rotational latencies.

* [Definition Source: Seagate Technology]

Webopedia Staff
Webopedia Staff
Since 1995, more than 100 tech experts and researchers have kept Webopedia’s definitions, articles, and study guides up to date. For more information on current editorial staff, please visit our About page.

Related Articles

@ Sign

Pronounced at sign or simply as at, this symbol is used in e-mail addressing to separate the user' name from the user's domain name,...

Munging

(MUHN-jing) Munging (address munging), is the act of altering an email address posted on a Web page to make it unreadable to bots and...

How to Create an RSS Feed

In the second installment of RSS how-to, we look at some of the nonrequired (optional) channel and item tags, discuss RSS specifications in-depth and...

Dictionary Attack

(n.) (1) A method used to break security systems, specifically password-based security systems, in which the attacker systematically tests all possible passwords beginning with...

ScalaHosting

ScalaHosting is a leading managed hosting provider that offers secure, scalable, and affordable...

HRIS

Human resources information system (HRIS) solutions help businesses manage multiple facets of their...

Best Managed Service Providers...

In today's business world, managed services are more critical than ever. They can...