LaCie eSATA PCI Card •
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eSATA Questions & Answers
User Manual
page 11
What is Serial ATA?
The Serial Advanced Technology Attachment (ATA) is the evo-
lutionary successor to the Parallel ATA/ IDE (Integrated Drive
Electronics) interface, which has been in use for the last twenty
years to connect peripheral devices to the computer. The Paral-
lel ATA standard can deliver data at a maximum of 133MB/s,
while Serial ATA provides for a data throughput of 150MB/s
with the initial release, and specification developers are planning
increased speeds over the next several years. Serial ATA removes
the performance bottleneck of the Parallel ATA specification, and
follows a clearly defined road-map to greater and greater data
transfer rates and feature improvements.
Deriving its name from the way that it transmits signals, in a
single stream, or serially, Serial ATA operates in a point-to-point
topology. This connectivity methodology delivers the entire avail-
able interface bandwidth to each device, allowing each device to
operate at its maximum throughput, and provides direct commu-
nication between the device and the system at any time, reducing
arbitration delays associated with shared bus topologies.
What are the features and benefits of
Serial ATA?
The Serial ATA specification provides several key advancements
that will help spur widespread implementation:
Performance: Serial ATA is a point-to-point topology, and does
not have to share the bus, instead dedicating full bandwidth to
the device. These dedicated links make creating a Serial ATA
RAID array quick and relatively inexpensive to implement.
Easy installation and configuration: There are no device IDs, ter-
mination or master/slave conflicts, and the standard supports
hot-plug connectivity. Drives can be added, upgraded or re-
moved without having to power down the whole system.
Improved reliability: Serial ATA also uses 32-bit cyclic redun-
dancy checking (CRC) on all transfers to ensure correct data
transmissions. Due to this CRC capability, Serial ATA performs
protection and recovery features at multiple levels: PHY layer,
link layer and transport and software layers.
Command optimization: Serial ATA utilizes Native Command
Queing (NCQ) and first party direct memory access (DMA) to
intelligently order commands in an internal queue within the
drive, without having to involve the host CPU. Judging its own
drive head’s angular and rotational position, the drive selects a
data transfer from the queue that will minimize both its seek and
rotational latencies.
Simplified structure: Serial ATA utilizes a more efficient signal-
ing voltage (250mV vs. 5V for Parallel ATA), and much smaller,
thinner and compact cables and connectors. Due to the simpli-
fied cabling (the reduction in the number of pins and wires), the
number of fault possibilities decreases.
Seamless integration: Serial ATA maintains register and software
compatibility with Parallel ATA, and should be transparent to
both the BIOS and operating system. Simply add more Serial
ATA links to increase the number of connectivity points in your
system.
What are the ideal uses of Serial ATA?
Although the specification supports all ATA and ATAPI devices
(i.e. CD, DVD, tape drives, etc.), and delivers superior perfor-
mance than both Hi-Speed USB 2.0 and FireWire/IEEE 1394,
external Serial ATA connectors are intended for storage devic-
es. Serial ATA works best in storage environments that require
high data throughput to deliver large files quickly and efficiently,
maximizing the storage systems utilization and enhancing overall
productivity.
Due to its performance, reliability, scalability and cost-effective-
ness, Serial ATA can be implemented in a wide-range of settings,
from desktop usage to network storage applications.
Cable and Connectors
Your LaCie drive is shipped with a eSATA cable, to ensure maxi-
mum data transfer performance when connected to a eSATA
port.
4. eSATA Questions & Answers
