What is the AHCI Mode ?

AHCI (the Advanced Host Controller Interface),in Intel's guidance, by the number of companies R & D interface standard, which allows the storage driver to enable advanced Serial ATA features such as Native Command Queuing and hot plug, its R & D team members include Intel, AMD, Dell, Marvell, Maxtor, Microsoft, Red Hat, Seagate and StorageGear famous enterprises.

The AHCI essence is a PCI class device to play the role of a common interface (ie, it is common to different operating systems and hardware), in between the internal logic of the system memory bus and Serial ATA devices. This device class describes the general system memory structure with control and status area, the command sequence entry table; each command table entry contains the SATA device programming information, and a point (used in the device and host transfer data) that describes the table pointer.

AHCI contains a PCI BAR (base address register), a native SATA function. Support the development of Serial ATA products successfully developed the AHCI unified interface, greatly simplified, operating system and device manufacturers, eliminating the need for the work of the separate development of the interface instead of directly operate in a unified interface, can be achieved, including many features, including NCQ (Native Command Queuing).

AHCI mode and IDE mode, installed the system will need to install the SATA drive (and it seems that this model can open the NCQ function).

RAID mode is to have two hard drives can be achieved, the specific circumstances can refer to the online form RAID article, if you only have one hard drive you can ignore it.

NCQ is a new hard drive technology, simply open it jump from one program to another program will be faster to achieve it we must first select AHCI in the BIOS mode, and then install the installed system the appropriate drive (usually in the motherboard driver disk), the installed system basically can be realized. Many SATA Device Controller can be individually enabled AHCI function or a combination of RAID functionality, Intel proposed to take AHCI mode to set up the RAID can be maximum flexibility in its support AHCI chipset RAID function, because the AHCI in the operation to complete the installation RAID set up mode switch system.

Windows Vista core has full support for AHCI, Linux version 2.6.19 of the core of the system from the support of other older operating systems you need the hardware manufacturer provides the driver can support.

SCSI hard drive performance in multi-task load has been praised for its fundamental reason for addition to the amazing interface rate of the SCSI interface is directive sorting capabilities. Past PATA, SATA hard drive also precisely because of the lack of an instruction to optimize the executive function and performance to lag behind SCSI hard disk. This dilemma, NCQ (Native Command Qu,) Intel AHCI 1.0 specification was first introduced, its application can significantly reduce the hard disk useless seek times and data lookup time, thus significantly enhance the multi-task case, hard drive the performance.

In addition, as an improved version of the SATA standard, Intel has improved the detailed specification of the Serial ATA II interface and the Serial ATA II R & D will belong to the second phase of the AHCI unified interface. Which has begun the first stage from 2006, many manufacturers have also introduced a Serial ATA interface products, including hard drive and motherboard. But this is only as a transition, in the second stage, Serial ATA II will by virtue of a higher signal transmission speed direct replacement for the SATA.



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