Sata cabling

[JS]

I doubt the short distance/length that a Fiber Optic
connected from a Hard Drive to the motherboard
would cause any significant skew.

See:
http://ieeexplore.ieee.org/Xplore/l...0871697.pdf?arnumber=871697&authDecision=-203

--
JS
http://www.pagestart.com

--
JS
http://www.pagestart.com




What about a Fiber cable?

[Top posting corrected]

If you mean a fibre optic cable, these are exclusively serial devices. It
would not be possible to operate a number of fibres as a parallel data
link because they suffer skew in the transmission times as well. Although
the effect is less marked than it is with copper, the ability to transmit
much shorter pulses of light brings the problem firmly back to the fore
again.

 

[Gerry]

Well JS the thread has skewed off topic<G>!. The topic was the reliabilty of
sata cable and connectors!


--


Gerry
~~~~
FCA
Stourport, England
Enquire, plan and execute
~~~~~~~~~~~~~~~~~~~

I doubt the short distance/length that a Fiber Optic
connected from a Hard Drive to the motherboard
would cause any significant skew.

See:
http://ieeexplore.ieee.org/Xplore/l...0871697.pdf?arnumber=871697&authDecision=-203

--
JS
http://www.pagestart.com



Well, in a crude sense think of SATA
as a two lane highway compared to
PATA as an 8 lane highway. If the PATA
cable design was updated to handle higher
transfer rates I would think that PATA could
be at least 4x faster than SATA.


Not possible. 1.33 Gb/s is the practical limit for a copper
parallel transmission line.

And an updated PATA cable need not be a
giant size ribbon cable either. Just imagine if
your ram memory was serial access instead
of DDR2 or DDR3.


Actually, serial RAM memory already exists, but it is only used in
very specialised applications due to the cost. It is, of course,
much much faster than the type of memory that is encountered in a
PC, but PC memory is largely hamstrung because it is based on
dynamic architecture which is far slower (and cheaper) than static
architecture. This is why your PC has a apir of processor caches
to speed RAM access up. The L2 cache is a chunk of static RAM
which is about 4 times faster than the main RAM and the L1 cache
is static RAM which is vastly faster than the L2 (and very
expensive - which is why it isn't very big). FLASH memory is
exclusively serial access.

What about a Fiber cable?

[Top posting corrected]

If you mean a fibre optic cable, these are exclusively serial
devices. It would not be possible to operate a number of fibres as
a parallel data link because they suffer skew in the transmission
times as well. Although the effect is less marked than it is with
copper, the ability to transmit much shorter pulses of light brings
the problem firmly back to the fore again.

 

[Gerry]

007

Can I drag you back to the topic of the thread? What has been your
experience with regard to the reliability of the connectors / cabling?


--


Gerry
~~~~
FCA
Stourport, England
Enquire, plan and execute
~~~~~~~~~~~~~~~~~~~

--
JS
http://www.pagestart.com




IEEE-488 can be daisy chained or Star configuration.
In addition an IEEE-488 cable could be removed from
the hard drive in the middle of transferring a file and then
attached again and the file xfer would complete with no
data lost, this was possible over 25 years ago, try that
with SATA or PATA!

[Top posting corrected - AGAIN]

Although PATA is not hot puggable, SATA is. I haven't tried pulling
the plug in the middle of a transfer, but I can't think of anything
that would prevent the completion of the transfer.

The fact that I can't think of anything, don't make it so though.

 

[JS]

Well said.

--
JS
http://www.pagestart.com

Well JS the thread has skewed off topic<G>!. The topic was the reliabilty
of sata cable and connectors!


--


Gerry
~~~~
FCA
Stourport, England
Enquire, plan and execute
~~~~~~~~~~~~~~~~~~~

I doubt the short distance/length that a Fiber Optic
connected from a Hard Drive to the motherboard
would cause any significant skew.

See:
http://ieeexplore.ieee.org/Xplore/l...0871697.pdf?arnumber=871697&authDecision=-203

--
JS
http://www.pagestart.com



Well, in a crude sense think of SATA
as a two lane highway compared to
PATA as an 8 lane highway. If the PATA
cable design was updated to handle higher
transfer rates I would think that PATA could
be at least 4x faster than SATA.


Not possible. 1.33 Gb/s is the practical limit for a copper
parallel transmission line.

And an updated PATA cable need not be a
giant size ribbon cable either. Just imagine if
your ram memory was serial access instead
of DDR2 or DDR3.


Actually, serial RAM memory already exists, but it is only used in
very specialised applications due to the cost. It is, of course,
much much faster than the type of memory that is encountered in a
PC, but PC memory is largely hamstrung because it is based on
dynamic architecture which is far slower (and cheaper) than static
architecture. This is why your PC has a apir of processor caches
to speed RAM access up. The L2 cache is a chunk of static RAM
which is about 4 times faster than the main RAM and the L1 cache
is static RAM which is vastly faster than the L2 (and very
expensive - which is why it isn't very big). FLASH memory is
exclusively serial access.


What about a Fiber cable?


[Top posting corrected]

If you mean a fibre optic cable, these are exclusively serial
devices. It would not be possible to operate a number of fibres as
a parallel data link because they suffer skew in the transmission
times as well. Although the effect is less marked than it is with
copper, the ability to transmit much shorter pulses of light brings
the problem firmly back to the fore again.

 

[JohnO]

I doubt the short distance/length that a Fiber Optic
connected from a Hard Drive to the motherboard
would cause any significant skew.

Perhaps not, but the issue with drives isn't the bus speed, it's the
platter-to-head speed. A $1 SATA cable can handle the max burst data rate
any HDD can deliver today, and lots more, too.

-John O

 

[Bill in Co.]

That's only part of the problem. Crosstalk can be minimised by good cable
design. That was the object of the 80 conductor (P)ATA cable which placed
a
grounded conductor either side of each signal carrying conductor. This
reduces crosstalk, but more importantly provides the signal with a
transmission path that more closely resembles an 'ideal' transmission
line.

But it isn't the cross talk that really limits the parallel system. It's
something called 'skew'. This is where the individual signals in the
individual transmission lines arive at the distant end of the cable at
different times. Low voltage diferential signalling was introduced on
some
systems to reduce crosstalk even further but there was no solution to the
problem of skew. Serial systems do not suffer from skew, hence the
transmission rates are higher.

I guess in the earlier days of PATA the crosstalk problem was significant
enough that the Ultra ATA helped considerably, but we are now past that, and
the signal skewing is the prinicipal limitation.

You mentioned the different propagation times down the different conductors,
but I'd also add that the individual signals in each parallel line
originating from the
signal source aren't perfectly in synch, either. IOW, the signal pulses in
each parallel line don't rise and fall together in perfect sync.

 

[M.I.5¾]

Well JS the thread has skewed off topic<G>!. The topic was the reliabilty
of sata cable and connectors!

When did the rule come in that threads were not permitted to go off at a
tangent?

--


Gerry
~~~~
FCA
Stourport, England
Enquire, plan and execute
~~~~~~~~~~~~~~~~~~~

I doubt the short distance/length that a Fiber Optic
connected from a Hard Drive to the motherboard
would cause any significant skew.

See:
http://ieeexplore.ieee.org/Xplore/l...0871697.pdf?arnumber=871697&authDecision=-203

--
JS
http://www.pagestart.com



Well, in a crude sense think of SATA
as a two lane highway compared to
PATA as an 8 lane highway. If the PATA
cable design was updated to handle higher
transfer rates I would think that PATA could
be at least 4x faster than SATA.


Not possible. 1.33 Gb/s is the practical limit for a copper
parallel transmission line.

And an updated PATA cable need not be a
giant size ribbon cable either. Just imagine if
your ram memory was serial access instead
of DDR2 or DDR3.


Actually, serial RAM memory already exists, but it is only used in
very specialised applications due to the cost. It is, of course,
much much faster than the type of memory that is encountered in a
PC, but PC memory is largely hamstrung because it is based on
dynamic architecture which is far slower (and cheaper) than static
architecture. This is why your PC has a apir of processor caches
to speed RAM access up. The L2 cache is a chunk of static RAM
which is about 4 times faster than the main RAM and the L1 cache
is static RAM which is vastly faster than the L2 (and very
expensive - which is why it isn't very big). FLASH memory is
exclusively serial access.


What about a Fiber cable?


[Top posting corrected]

If you mean a fibre optic cable, these are exclusively serial
devices. It would not be possible to operate a number of fibres as
a parallel data link because they suffer skew in the transmission
times as well. Although the effect is less marked than it is with
copper, the ability to transmit much shorter pulses of light brings
the problem firmly back to the fore again.

 

[M.I.5¾]

I doubt the short distance/length that a Fiber Optic
connected from a Hard Drive to the motherboard
would cause any significant skew.

Ignoring the issue of the mechanical limitations, the whole point to using
fibre over copper would be to take advantage of the much higher data speeds
that are available. At those high speeds, skew certainly is a significant
issue even over a foot of fibres.

See:
http://ieeexplore.ieee.org/Xplore/l...0871697.pdf?arnumber=871697&authDecision=-203

--
JS
http://www.pagestart.com

--
JS
http://www.pagestart.com



Well, in a crude sense think of SATA
as a two lane highway compared to
PATA as an 8 lane highway. If the PATA
cable design was updated to handle higher
transfer rates I would think that PATA could
be at least 4x faster than SATA.


Not possible. 1.33 Gb/s is the practical limit for a copper parallel
transmission line.

And an updated PATA cable need not be a
giant size ribbon cable either. Just imagine if
your ram memory was serial access instead
of DDR2 or DDR3.


Actually, serial RAM memory already exists, but it is only used in very
specialised applications due to the cost. It is, of course, much much
faster than the type of memory that is encountered in a PC, but PC
memory is largely hamstrung because it is based on dynamic architecture
which is far slower (and cheaper) than static architecture. This is
why your PC has a apir of processor caches to speed RAM access up. The
L2 cache is a chunk of static RAM which is about 4 times faster than
the main RAM and the L1 cache is static RAM which is vastly faster than
the L2 (and very expensive - which is why it isn't very big).

FLASH memory is exclusively serial access.

What about a Fiber cable?

[Top posting corrected]

If you mean a fibre optic cable, these are exclusively serial devices.
It would not be possible to operate a number of fibres as a parallel data
link because they suffer skew in the transmission times as well.
Although the effect is less marked than it is with copper, the ability to
transmit much shorter pulses of light brings the problem firmly back to
the fore again.

 

[M.I.5¾]

007

Can I drag you back to the topic of the thread? What has been your
experience with regard to the reliability of the connectors / cabling?

I have not (yet!) experienced a failure or indeed any problem with a SATA
connector (either data or power). But to put that in perspective, I do
occasionally swap the connectors between two disc drives in my desktop PC,
but I doubt that I have done it 50 times yet. I do not recall an incident
where the connector has become dislodged for any reason.

 

[M.I.5¾]

IEEE-488 can be daisy chained or Star configuration.
In addition an IEEE-488 cable could be removed from
the hard drive in the middle of transferring a file and then
attached again and the file xfer would complete with no
data lost, this was possible over 25 years ago, try that
with SATA or PATA!

It's just occured to me that IEEE-488 is not (officially at least) a hot
pluggable system.

 

[M.I.5¾]

Well said.

You started it!

--
JS
http://www.pagestart.com

Well JS the thread has skewed off topic<G>!. The topic was the reliabilty
of sata cable and connectors!


--


Gerry
~~~~
FCA
Stourport, England
Enquire, plan and execute
~~~~~~~~~~~~~~~~~~~

I doubt the short distance/length that a Fiber Optic
connected from a Hard Drive to the motherboard
would cause any significant skew.

See:
http://ieeexplore.ieee.org/Xplore/l...0871697.pdf?arnumber=871697&authDecision=-203



--
JS
http://www.pagestart.com



Well, in a crude sense think of SATA
as a two lane highway compared to
PATA as an 8 lane highway. If the PATA
cable design was updated to handle higher
transfer rates I would think that PATA could
be at least 4x faster than SATA.


Not possible. 1.33 Gb/s is the practical limit for a copper
parallel transmission line.

And an updated PATA cable need not be a
giant size ribbon cable either. Just imagine if
your ram memory was serial access instead
of DDR2 or DDR3.


Actually, serial RAM memory already exists, but it is only used in
very specialised applications due to the cost. It is, of course,
much much faster than the type of memory that is encountered in a
PC, but PC memory is largely hamstrung because it is based on
dynamic architecture which is far slower (and cheaper) than static
architecture. This is why your PC has a apir of processor caches
to speed RAM access up. The L2 cache is a chunk of static RAM
which is about 4 times faster than the main RAM and the L1 cache
is static RAM which is vastly faster than the L2 (and very
expensive - which is why it isn't very big). FLASH memory is
exclusively serial access.


What about a Fiber cable?


[Top posting corrected]

If you mean a fibre optic cable, these are exclusively serial
devices. It would not be possible to operate a number of fibres as
a parallel data link because they suffer skew in the transmission
times as well. Although the effect is less marked than it is with
copper, the ability to transmit much shorter pulses of light brings
the problem firmly back to the fore again.

 

[Gerry]

007

I am sure that as a long term contributor to these newsgroups you are aware
of conventions. What is off topic and what is going off on a tangent is
something we could debate for ever and a day. I go off on a tangent myself
at times so it is no big issue here. Suffice it to say I just wanted to gain
the views of those coming late to the thread on the original question I
posed on 21 March.

From a friend I got these comments.
"In my view, the SATA 'Connector' is an engineering blunder. A sort-of flat
sleeve slides over a notched part on the edge of the board whereupon sit
some exposed/un-insulated traces. Flat conductors encased within a plastic
bit are slid into contact with them. There is no mechanism but friction to
keep the 'connector' in place. Entirely inadequate. It is not designed for
repeated make/break insertion/removal. If subjected even to a low number of
such operations (design spec is 50), it will fail. (5 000 for an eSATA
connector). If I have to repeatedly disconnect-connect a drive during
testing, I replace the cable as a matter of routine."

I am interested in knowing whether others have encountered this problem and
how common place it is?

--


Gerry
~~~~
FCA
Stourport, England
Enquire, plan and execute
~~~~~~~~~~~~~~~~~~~

Well JS the thread has skewed off topic<G>!. The topic was the reliabilty
of sata cable and connectors!

When did the rule come in that threads were not permitted to go off at a
tangent?

--


Gerry
~~~~
FCA
Stourport, England
Enquire, plan and execute
~~~~~~~~~~~~~~~~~~~

I doubt the short distance/length that a Fiber Optic
connected from a Hard Drive to the motherboard
would cause any significant skew.

See:
http://ieeexplore.ieee.org/Xplore/l...0871697.pdf?arnumber=871697&authDecision=-203



--
JS
http://www.pagestart.com



Well, in a crude sense think of SATA
as a two lane highway compared to
PATA as an 8 lane highway. If the PATA
cable design was updated to handle higher
transfer rates I would think that PATA could
be at least 4x faster than SATA.


Not possible. 1.33 Gb/s is the practical limit for a copper
parallel transmission line.

And an updated PATA cable need not be a
giant size ribbon cable either. Just imagine if
your ram memory was serial access instead
of DDR2 or DDR3.


Actually, serial RAM memory already exists, but it is only used in
very specialised applications due to the cost. It is, of course,
much much faster than the type of memory that is encountered in a
PC, but PC memory is largely hamstrung because it is based on
dynamic architecture which is far slower (and cheaper) than static
architecture. This is why your PC has a apir of processor caches
to speed RAM access up. The L2 cache is a chunk of static RAM
which is about 4 times faster than the main RAM and the L1 cache
is static RAM which is vastly faster than the L2 (and very
expensive - which is why it isn't very big). FLASH memory is
exclusively serial access.


What about a Fiber cable?


[Top posting corrected]

If you mean a fibre optic cable, these are exclusively serial
devices. It would not be possible to operate a number of fibres as
a parallel data link because they suffer skew in the transmission
times as well. Although the effect is less marked than it is with
copper, the ability to transmit much shorter pulses of light brings
the problem firmly back to the fore again.

 

[JohnO]

We put computers in the hands of students for the purposes of teaching how
they work and how to fix them. While SATA connectors are FAR more reliable
than 40-pin, we see some of the HDD connectors break off. The pins are good
but the plastic in the connector is gone. Wouldn't have believed it could
happen without abuse until I did it myself. The connector is really just
sticking out there, very little mechanical support in all of the drives I've
seen. Even mobos have better support for the connector.

-John O

 

[Leythos]

We put computers in the hands of students for the purposes of teaching how
they work and how to fix them. While SATA connectors are FAR more reliable
than 40-pin, we see some of the HDD connectors break off. The pins are good
but the plastic in the connector is gone. Wouldn't have believed it could
happen without abuse until I did it myself. The connector is really just
sticking out there, very little mechanical support in all of the drives I've
seen. Even mobos have better support for the connector.

SATA connectors are unreliable, they are easy to dislodge, they are not
anywhere near as reliable as the IDE connectors.

SATA makes it nice for cable management, but, if BOTH ends are not
fitted with a snap lock, there is a good chance that you will bump one
loose at some point in your tinkering - the same is not true with the
older style connectors.

 

[JS]

While its not mentioned as "Hot Pluggable" I've
seen it demonstrated.

Also while at RCA's Princeton Labs I've
seen the cable daisy chained well beyond
the maximum IEEE specified length.

 

[JS]

Which I just did when replacing some
memory sticks, one little nudge and the
cable was no longer all the way inserted
into the hard drive.

I like the idea mentioned earlier about
applying a small amount some type of RTV.

 

[Leythos]

While its not mentioned as "Hot Pluggable" I've
seen it demonstrated.

Also while at RCA's Princeton Labs I've
seen the cable daisy chained well beyond
the maximum IEEE specified length.

And there are controllers for IDE that are hot pluggable also.

The new connectors should have been designed with a catch/latch system
of some sort to start with.

 

[M.I.5¾]

We put computers in the hands of students for the purposes of teaching how
they work and how to fix them. While SATA connectors are FAR more reliable
than 40-pin, we see some of the HDD connectors break off. The pins are
good but the plastic in the connector is gone. Wouldn't have believed it
could happen without abuse until I did it myself. The connector is really
just sticking out there, very little mechanical support in all of the
drives I've seen. Even mobos have better support for the connector.

Having taught students for a few years, I am only too aware that they supply
the best survivability testing in the known engineering world.

I have to admit though that the connector design does leave a lot to be
desired.

 

[M.I.5¾]

While its not mentioned as "Hot Pluggable" I've
seen it demonstrated.

Also while at RCA's Princeton Labs I've
seen the cable daisy chained well beyond
the maximum IEEE specified length.

The maximum length is determined by attenuation of the signal, reflections
from the far end merging with the next pulse or 'chirping'* of the pulses
(only usually a problem with long lengths of rubbish cable). At the data
rate of IEEE-488, attenuation is likely to be the problem. If the cable and
connectors used are good quality, it is often possible to exceed the
'maximum' length (which is really the minimum length that it should still
work).

* The characteristic that different parts of the frequency spectrum
propagate at different speeds, the higher frequencies propagating more
slowly.