SATA Transport Layer 243
4.3.1 Introduction to NCQ
Accessing media on mass storage devices, such as hard disc drives (HDD), can have a negative impact
on overall system performance.
Unlike other purely electrical components in a modern system, HDDs are still largely mechanical
devices.
Drives are hampered by the inertia of their mechanical components, which effectively limits the
speed of media access and retrieval of data.
Mechanical performance can be physically improved only up to a certain point, and these perfor-
mance improvements usually come at an increased cost of the mechanical components.
However, intelligent internal management of the sequence of mechanical processes can greatly
improve the efficiency of the entire work ...