I got a PATA drive??

[Paul Dufresne]

On Sun, 29 Apr 2007 14:39:20 +1000, "Daniel Pittman"
<daniel at rimspace.net> said:
> 
> The traditional PATA disks then migrated to the same infrastructure
> because it allowed significant technical and practical improvements in
> their support in the kernel.

I just learned that I was using a PATA disk!
I had to read: http://www.rtcmagazine.com/home/article.php?id=100442
to really figure out what it is about.

My summary:
"The PATA interface, commonly called ATA, is also known as IDE."
Now that we have Serial AT Attachment, we begin to
call our traditional ATA (IDE), Parallel ATA (PATA).

What used to dinstinguish SCSI from IDE:
  * On physical side: "The SCSI controller that connects the storage
  media and the
CPU manages a complex parallel protocol to deliver storage deployment
scalability by
efficiently supporting up to 15 devices and one controller." (much
better than
master/slave we have on IDE)
  * On 'software' side: "The SCSI bus protocol allows computer systems
  to optimize
parallel transfers through the use of disconnect and command queuing
features not
used in IDE buses." Also, I was told SCSI is much more secure to power
interruption.

So, the new SATA (Serial AT Attachment) use the same 'software' as plain
old IDE,
on a new serial connector. "Serial ATA uses a point-to-point dedicated
bus and
eliminates the master/slave shared bus. It employs high-speed serial
cable in
lieu of the low reliability parallel bus ribbon cable."

I never really understood why using 80 wires on 40 wires connector
helped avoid
noise. "Instead of legacy 5V signals to increase signal integrity and
provide
compatibility with 3.3V-based systems, PATA uses Low Voltage
Differential
Signaling (LVDS)." That I understand, by using two wires to transport
signal, if
the wire get some noise making both wires getting +1 volt, the
difference between
the two wires (+1 volt minus +1 volt) will be null, so the noise have
been
'eliminated'.

"Serial Attached SCSI (SAS)is a successor of parallel SCSI. This new
interface
maintains the reliability, performance and robust command set of SCSI,
provides the
benefit of higher bus speeds offered by a serial bus and includes SATA
functions.
It uses the same physical layer interface as SATA drives, including the
connector,
as well as LVDS. Utilizing a dual-function controller and storage device
drivers,
system integrators can choose either SATA or SAS for their storage
systems."
The same very good 'software' as old SCSI, on the new SATA connector.

I wonder if that means that eventually, SAS will replace SATA. I sure
would like
to have SAS for the price of SATA.

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