NCQ (Native Command Queuing)

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NCQ (Native Command Queuing)

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Definition

NCQ enables several requests to be sent to the hard disk at the same time and the hard disk then decides for itself in which order it will process them. By avoiding unnecessary head movements, throughput and especially latency can be improved. The drive itself, the controller and the driver must support command queuing in order to use it.

However, due to the delays caused by NCQ, it is also possible that this procedure can lead to worse access times for some applications. The phenomenon can occur with games and sequential reading processes.

Native Command Queuing was introduced by Seagate for SATA drives in 2003. Apart from minor differences, it is similar to Tagged Command Queuing (TCQ), which has been supported by SCSI drives since the early 1990s. Unusual for ATA drives, TCQ was introduced here only by IBM in 2002 (IBM Deskstar 180GXP), but was hardly used due to lack of support from the controller side.

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References

1. Wikipedia: https://en.wikipedia.org/wiki/Native_Command_Queuing

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