AHCI and RAID on HP Elite 8100 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 consider-
ations, 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 dc7900 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 Busi-
ness PCs, which had a default SATA emulation mode of IDE (legacy).
RAID SATA emulation mode includes AHCI functionality. Customers with 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 _GTF (Get Task File) ACPI control method while in AHCI mode. However, a
Registry key is required to enable the port(s). See _GTF Support 8 section below.