Hardware Reference
In-Depth Information
as on PATA systems. Depending on the system, SATA interfaces might be enabled by de-
details.)
If you want to use SATA drives but don't want to install a new motherboard with SATA
host adapters already included, you can install a separate SATA host adapter into a PCI
expansion slot (see
Figure 7.11
)
. Most of these adapters include ATA RAID functions.
Figure 7.11
Typical 4-port SATA RAID host adapter.
Some of the first SATA host adapters, such as models from HighPoint and 3Ware, use a
PATA-to-SATA bridge technology that consumes as much as half of the available band-
width. Other adapters, such as those made by Promise Technology, use native SATA con-
trollerchips,whichisabettersolutionintheorybecauseitpreservesallthebandwidthfor
use by the drive. However, current SATA drives, like their PATA siblings, cannot transfer
data at anything close to the maximum rate of the host adapter; 80-90MBps is the typical
range for average transfer speeds of 7200 rpm SATA 3Gbps drives.
Advanced Host Controller Interface (AHCI)
SATA was designed not only as a replacement for PATA, but as an interface that would
evolve into something with many more capabilities and features than its predecessor. Ini-
tially,compatibilitywithPATAwasoneofthemostimportantfeaturesofSATAbecauseit
enabled a smooth and easy transition from one to the other. This compatibility extends to
