Many SATA controllers offer selectable modes of operation: legacy Parallel ATA, standard AHCI-mode, or vendor-specific RAID. Intel recommends choosing RAID mode on their motherboards (which also enables AHCI) rather than the plain AHCI/SATA mode for maximum flexibility, due to the issues caused when the mode is switched once an operating system has already been installed.
Legacy-mode is a software backward-compatibility mechanism intended to allow the SATA-controller to run in legacy operating-systems which are not SATA-aware.
AHCI is fully supported out of the box for Microsoft Windows Vista and the Linux operating system from kernel 2.6.19.
NetBSD also supports drivers in AHCI mode out of the box in certain versions.
OpenBSD has had an ahci driver since OpenBSD 4.1.
FreeBSD supports AHCI as well.
AHCI support for Solaris 10 has been introduced in the 8/07 release .
Older operating systems require hardware-specific drivers to support AHCI.
AHCI provides several features for SATA devices. These include hot plug functionality and power management functionality. For more information about the AHCI specification, visit the following Intel Web site: