..a short but sweet overview of SATA and SAS from Adaptec.
SATA is a replacement for IDE (or ATA). SAS is a replacement for
SCSI. Both replacements provide faster access, more devices, and
longer, thinner cables.
As usual, SATA is pitched at the low end of the market, while SAS is
pitched at the enterprise.
I note that despite a very long war of attrition from the IDE camp,
SCSI remains the interface of choice for "real" machines.
(you'll prob need to remove spaces from that URL for it to work)
"Tightening IT budgets are increasing pressure on organizations to
use system resources with greater efficiency as they look to data
centers to serve more clients. More than ever, IT managers must
choose technologies that make the most efficient use of their server
and storage components as the amount information they manage
continues to grow. One system resource that has come under increasing
scrutiny is the storage system. The reason: these systems are at the
heart of a data center's ability to make digitized data available
24x7, seamlessly scale capacity and increase server storage
performance while reducing the cost of managing information.
Data centers have relied on the parallel bus interface as the
workhorse disk drive interconnect for more than 20 years. Parallel
technologies remain in widespread use and continue to meet the
performance requirements of many of today's enterprise solutions.
However, significant technical challenges have made it economically
impractical to use parallel technologies to meet increasing demand
for more robust data integrity, higher system performance, greater
storage flexibility and scalability, and smaller system designs.
On a parallel bus, for example, slight length variations and other
small differences in individual wires make it difficult to
synchronize the arrival of signals at the receiver and to determine
when it needs to sample (or clock) the signals, a process called
clock skew, one factor that limits system performance. In addition,
parallel signal transmissions are susceptible to crosstalk across
wide data paths that add line noise and can cause signal errors - a
pitfall that has been remedied by slowing the signal, limiting trace
length or both. Terminating parallel signals is another difficulty,
requiring that individual lines be terminated, usually by the last
device, to avoid signal reflection at the end of a cable. Finally,
parallel's large cable and connector size make it unsuitable for
increasingly dense computing environments.
Serial architectures have emerged to deliver higher performance by
allowing more bandwidth per device pathway than their parallel
counterparts. Serial architecture connections consist of a single
pair of transmission signals that contain an embedded clock for self-
clocking, enabling clock speed to be easily scaled. Serial bus
architectures also support a network of dedicated point-to-point
device connections, versus the multi-drop architectures of parallel
buses, to deliver full bandwidth to each device, eliminate the need
for bus arbitration, reduce latency, and greatly simplify hot-plug
and hot-swap system implementations. This dedicated serial connection
also eliminates the single point of failure found in today's parallel
environments."
Stu
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* Origin: [adminz] tech, security, support (192.168.0.2)
generated by msg2page 0.06 on Jul 21, 2006 at 19:04:12
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