SATA and ATA

[Folkert Rienstra]

And when SATA starts running at fibre-channel speeds, then maybe that

will have some relevance.

It will never.
Sata is (basically) point-to-point. Parallel SCSI is not (multidrop).
FC is not (well not in the same sense that SATA is).
Comparing them on a one drive performance basis is pointless.
Comparing them on multiple drive performance basis has more sense.
That is where SATA-300 comes in and SATA Raid_in_a_box.

But in point of fact it's running slower than parallel-SCSI speeds,

No it's not, clock wise, and even then SATA doesn't need to be faster than
P-SCSI because P-SCSI needs to sustain 4 drives at once vs SATA only 1.
The comparison should be 2 drive P-ATA vs 4-drive P-SCSI.
The question is: Can one build Ultra-333 P-ATA to compete with Fast-320
(Ultra-640) SCSI without sacrificing P-ATA compatability.
Probably not, and even if one can, at what cost?

which clearly demonstrates that it was not needed for any technological reason.

No it does not.
SCSI was alway meant to be a bus. IDE was meant to be a 2-device interface.
There may be other reasons why SCSI can be scaled up without loosing
compatability and why IDE can not.
You can't just say that if SCSI can, then IDE can too.

 

[J. Clarke]

SCSI has already extended to Fiber Channel, now going SAS.

SO WHAT? What do you percieve that that has to do with SATA?

Oh, short lived PCI-X.

I'm sorry, but that statement makes no sense at all. PCI-X is parallel in
the purely conventional sense and has been around for a long time and
appears likely to remain around for a long time, as even Intel, which is
pushing PCI Express, nonetheless uses PCI-X internally in their chipset and
also on their purpose-made server board. However, PCI EXPRESS, which is
NOT REPEAT NOT PCI-X, uses up to 16 "lanes" to get its performance, so is
it serial or is it parallel?

So on reassembly of multiple (serialy propagated) data lines there is no
signal
skew between them? How come?

Each line is independently clocked. If you want the details ask Intel.

Crosstalk was greatly reduced by a special signal coding technigue to
reduce noise generation.

Oh? What is this "special coding technique" and where is it documented?

But the biggest change is in the concept. Less hard wired signals, more
virtual wires which deliver information not by direct electrical state but
by
content of data passed through them. Message Signaled Interrupt is an
example.

All of those techiques called for a new standard(s). But serial
communication
is the real engine in all of them (PCI Express, SAS, SATA).

Fine, believe what you want to. Since you don't seem to know the difference
between PCI-X and PCI Express and seem to think that high end extensions of
SCSI have some relevance to the ability of a parallel architecture to
deliver SATA performance, which the parallel SCSI architecture clearly
does, it's clear to me that any further attempt at discussion with you is
pointless.

 

[Nick]

Try to read about a signal skew:
http://www.powerdesign365.com/Power_interconnects/Article29003.aspx

Excellent article Peter.

Nick

 

[dg]

(a) you're not _required_ to use 2 per cable
(b) that 72 MB/sec is for sequential transfers on the outermost zone. In
the real world you'd hardly ever see that transfer rate even with an
infinite-speed interface.

You forgot (c), raptors are not PATA drives. So 2 raptors saturating PATA
is again another moot point.

Probably a typo here, as far as I know there are no 10,000 RPM PATA drives
yet there ARE 10,000 RPM SATA drives.

 

[Derek Baker]

You forgot (c), raptors are not PATA drives. So 2 raptors saturating PATA
is again another moot point.

I introduced the Raptors, as an example.

 

[Folkert Rienstra]

SO WHAT? What do you percieve that that has to do with SATA?

Does the term 'Serial' ring a bell?

I'm sorry, but that statement makes no sense at all.

Actually it does. PCI-X never really caught on.
PCIe on the other hand appears to catch on almost immediately, replacing
AGP also.

PCI-X is parallel in the purely conventional sense and has been around
for a long time

But hardly ever used except for the very latest high-end SCSI and SATA.

and appears likely to remain around for a long time, as even Intel, which is
pushing PCI Express, nonetheless uses PCI-X internally in their chipset and
also on their purpose-made server board. However, PCI EXPRESS, which is
NOT REPEAT NOT PCI-X, uses up to 16 "lanes" to get its performance, so is
it serial or is it parallel?


Each line is independently clocked.

So obviously there's skew.

If you want the details ask Intel.


Oh? What is this "special coding technique" and where is it documented?

SERDES and 8B/10B data encoding.

Fine, believe what you want to.

Since you don't seem to know the difference between PCI-X and PCI Express

Oh?
Where exactly did he 'seemingly' display that? It's you who obviously doesn't
understand PCIe.
All you appear doing is desperate arm waving and jumping up and down hoping
that someone will believe you over him.

and seem to think that high end extensions of SCSI have some relevance
to the ability of a parallel architecture to deliver SATA performance,

Whatever that gibberjabber is supposed to mean.
If anything, that is what you appear to think.

which the parallel SCSI architecture clearly does,

it's clear to me that any further attempt at discussion with you is pointless.

Have to agree there but obviously for other reasons.

 

[Joe Doe]

What technical differences are between SATA and ATA?

On Anandtech's review of dual core processors he pointed out that NCQ
which SATA supports has a strong impact on multitasking tests:

See:

http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2389&p=8

for Seagate's take on NCQ:

http://www.seagate.com/products/interface/sata/benchmark.html


I certainly would like to surf wile compressing video in the background
among other tasks. If NCQ and SATA offer an advantage in this scenario
I would consider it a big enough incentive for me to want to migrate to
SATA drives with NCQ support.

Roland