AHCI and RAID on HP Compaq Elite 8000, 8100, and 8200 Business PCs

5
Benefits of AHCI
AHCI provides several benefits:
• Elimination of master/slave handling
• Native Command Queuing (NCQ)
• Hot-plugging
AHCI mode eliminates the master/slave topology for cabling SATA hard drives.
Hardware and software that emulate IDE still have some limitations with the
master/slave topology that came from the Parallel ATA (PATA) mass storage
implementation. With AHCI mode, there is no need to worry about cabling
considerations, other than the boot drive should be on the lowest numbered SATA
port (dark blue connector). SATA ports are independent of each other and are not
tied together by master/slave relationship.
Native Command Queuing (NCQ) is technology that allows a SATA device to
internally optimize the order of command execution for increased performance.
Commands sent to a NCQ-capable SATA device are placed in an internal queue
where they can be dynamically and intelligently re-ordered and tracked.
Hot-plugging is the ability to insert a SATA device into a running system and have
the operating system recognize the device. AHCI is required for eSATA hot-plug
functionality. Refer to the “Using eSATA on HP Compaq Business PCs” white paper
for more information about eSATA hot-plugging.
BIOS / Software / Hardware Considerations
BIOS Interface
SATA Emulation Mode
SATA emulation mode can be set in F10 Setup by selecting Storage > Storage
Options > SATA Emulation > Default - AHCI.
SATA emulation mode is set to AHCI by default. This is a change from previous HP
Compaq dc7xxx Business PCs, which had a default SATA emulation mode of IDE
(legacy).
RAID SATA emulation mode includes AHCI functionality. Customers purchasing a
RAID system do not need to make any changes in F10 Setup.
BIOS Support for _GTF in ACPI Mode
The system BIOS supports the Get Task File (_GTF) ACPI control method while in
AHCI mode. However, a Registry key is required to enable the port(s). See the
_GTF Support section for more information.