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Old 01-21-2008, 05:16 PM
"Mikkel L. Ellertson"
 
Default HELP: External 250G USB screwed with GParted

Mikkel L. Ellertson wrote:
I could have sworn that the CAT 3 cable I used for networking was 4
pair, and not 2 pair. I can remember some 2 pair cable use for POT
connections, but every networking application was 4 pair. Now, both
10BaseT and 100BaseTx only use 2 pair, but the cable is normally 4 pair.
Now, there is a difference a physical difference between CAT 3 and CAT
5, but it has more to do with how the pairs are twisted together then
the number of wires. The number of wists/inch, and the relationship
between the number of twists in each pair change the electrical
characteristics of the cable. (Each pair has a different twist rate.) I
think how the pairs are twisted together in the cable is also specified.


Not enough coffee - Both CAT 3 and CAT 5 cable are available in
different number of pairs, but 4 pair tends to be the most common in
CAT 5 and CAT5e. You want to have fun, try terminating a 100 pair
CAT 3 cable. At least with CAT 5, they tend to bundle each set of 5
pair in their own jacket inside the main cable. (I would rather have
them bundled in 4 pair groups - I hate wasting 5 pair of a 25 pair
cable when doing networking. I would rather have 5 groups of 4 pair
for a 20 pair cable.)


Mikkel
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Old 01-21-2008, 05:53 PM
Rick Stevens
 
Default HELP: External 250G USB screwed with GParted

On Mon, 2008-01-21 at 12:16 -0600, Mikkel L. Ellertson wrote:
> Mikkel L. Ellertson wrote:
> > I could have sworn that the CAT 3 cable I used for networking was 4
> > pair, and not 2 pair. I can remember some 2 pair cable use for POT
> > connections, but every networking application was 4 pair. Now, both
> > 10BaseT and 100BaseTx only use 2 pair, but the cable is normally 4 pair.
> > Now, there is a difference a physical difference between CAT 3 and CAT
> > 5, but it has more to do with how the pairs are twisted together then
> > the number of wires. The number of wists/inch, and the relationship
> > between the number of twists in each pair change the electrical
> > characteristics of the cable. (Each pair has a different twist rate.) I
> > think how the pairs are twisted together in the cable is also specified.
> >
> Not enough coffee - Both CAT 3 and CAT 5 cable are available in
> different number of pairs, but 4 pair tends to be the most common in
> CAT 5 and CAT5e. You want to have fun, try terminating a 100 pair
> CAT 3 cable. At least with CAT 5, they tend to bundle each set of 5
> pair in their own jacket inside the main cable. (I would rather have
> them bundled in 4 pair groups - I hate wasting 5 pair of a 25 pair
> cable when doing networking. I would rather have 5 groups of 4 pair
> for a 20 pair cable.)

Most CAT5e 25-pair I've seen don't bundle five pairs in a separate
jacket...it's just a standard 25-pair telco cable that meets 5e specs
(and I've even seen CAT6 versions of the same cable).

I've used the 5e stuff a BUNCH of times...typically to cross-connect
racks using 24-port patch panels. Each panel requires four 25-pair
cables and you sacrifice a single pair per 25-pair cable. I've pushed
gigabit across it with no problems--I've even pushed 10GB across it with
a bit less success (haven't tried the CAT6 version, but I don't design
data centers much anymore).
>
> Mikkel
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----------------------------------------------------------------------
- Rick Stevens, Principal Engineer rstevens@internap.com -
- CDN Systems, Internap, Inc. http://www.internap.com -
- -
- Never test for an error condition you don't know how to handle. -
----------------------------------------------------------------------

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Old 01-21-2008, 06:22 PM
"Mikkel L. Ellertson"
 
Default HELP: External 250G USB screwed with GParted

Rick Stevens wrote:

On Mon, 2008-01-21 at 12:16 -0600, Mikkel L. Ellertson wrote:
Not enough coffee - Both CAT 3 and CAT 5 cable are available in
different number of pairs, but 4 pair tends to be the most common in
CAT 5 and CAT5e. You want to have fun, try terminating a 100 pair
CAT 3 cable. At least with CAT 5, they tend to bundle each set of 5
pair in their own jacket inside the main cable. (I would rather have
them bundled in 4 pair groups - I hate wasting 5 pair of a 25 pair
cable when doing networking. I would rather have 5 groups of 4 pair
for a 20 pair cable.)


Most CAT5e 25-pair I've seen don't bundle five pairs in a separate
jacket...it's just a standard 25-pair telco cable that meets 5e specs
(and I've even seen CAT6 versions of the same cable).

I've used the 5e stuff a BUNCH of times...typically to cross-connect
racks using 24-port patch panels. Each panel requires four 25-pair
cables and you sacrifice a single pair per 25-pair cable. I've pushed
gigabit across it with no problems--I've even pushed 10GB across it with
a bit less success (haven't tried the CAT6 version, but I don't design
data centers much anymore).
I wonder it the difference was that we were using all plenum rated
cable? We were running between floors and through firewalls. Like
you, we had 24 port rack mounted patch panels on both ends. We also
had routers and a lot of patch panels for wall jacks on one end. The
other end was in the server room. (About 500,000' of 4 pair CAT 5
installed.)


Mikkel
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Old 01-21-2008, 07:22 PM
Lamar Owen
 
Default HELP: External 250G USB screwed with GParted

On Monday 21 January 2008, Craig White wrote:
> The guy from tech
> support told me that he was unconcerned and that if the cable appeared
> to be undamaged, it in all likelihood wasn't the problem and that in his
> view, all commercially available USB device cables (6 foot and less)
> were suitable for using with their USB 2.0 drives.

> I have seen nothing to disprove that statement, either from my own
> experience nor even the anecdotal experience of others. Only Tim's
> theories and Tim is long on theories.


There was a slip of paper in the box with my 80GB WD PassPort drive that
warned to always use the supplied cable, and that the drive might not work
with other cables, and to not use extensions. My own experience trying to
use another cable, one that was the same length but had been supplied with a
USB multi-card reader (SanDisk branded), indicated that this was in fact
true, as the PassPort did not spin up with the SanDisk USB 2.0 cable, but
would with the supplied WD cable.

Please see
http://wdc.custhelp.com/cgi-bin/wdc.cfg/php/enduser/std_adp.php?p_faqid=1336&p_created=1112290978&p_si d=cVO3XkWi&p_accessibility=0&p_redirect=&p_lva=&p_ sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3J vd19jbnQ9Mjk2LDI5NiZwX3Byb2RzPTAmcF9jYXRzPTAmcF9wd j0mcF9jdj0mcF9zZWFyY2hfdHlwZT1hbnN3ZXJzLnNlYXJjaF9 mbmwmcF9wYWdlPTEmcF9zZWFyY2hfdGV4dD1zdXBwbGllZCBjY WJsZQ**&p_li=&p_topview=1
and
http://wdc.custhelp.com/cgi-bin/wdc.cfg/php/enduser/std_adp.php?p_faqid=1297&p_created=1102368573&p_si d=cVO3XkWi&p_accessibility=0&p_redirect=&p_lva=&p_ sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3J vd19jbnQ9Mjk2LDI5NiZwX3Byb2RzPTAmcF9jYXRzPTAmcF9wd j0mcF9jdj0mcF9zZWFyY2hfdHlwZT1hbnN3ZXJzLnNlYXJjaF9 mbmwmcF9wYWdlPTEmcF9zZWFyY2hfdGV4dD1zdXBwbGllZCBjY WJsZQ**&p_li=&p_topview=1
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Old 01-21-2008, 11:15 PM
Craig White
 
Default HELP: External 250G USB screwed with GParted

On Mon, 2008-01-21 at 15:22 -0500, Lamar Owen wrote:
> On Monday 21 January 2008, Craig White wrote:
> > The guy from tech
> > support told me that he was unconcerned and that if the cable appeared
> > to be undamaged, it in all likelihood wasn't the problem and that in his
> > view, all commercially available USB device cables (6 foot and less)
> > were suitable for using with their USB 2.0 drives.
>
> > I have seen nothing to disprove that statement, either from my own
> > experience nor even the anecdotal experience of others. Only Tim's
> > theories and Tim is long on theories.
>
>
> There was a slip of paper in the box with my 80GB WD PassPort drive that
> warned to always use the supplied cable, and that the drive might not work
> with other cables, and to not use extensions. My own experience trying to
> use another cable, one that was the same length but had been supplied with a
> USB multi-card reader (SanDisk branded), indicated that this was in fact
> true, as the PassPort did not spin up with the SanDisk USB 2.0 cable, but
> would with the supplied WD cable.
>
> Please see
> http://wdc.custhelp.com/cgi-bin/wdc.cfg/php/enduser/std_adp.php?p_faqid=1336&p_created=1112290978&p_si d=cVO3XkWi&p_accessibility=0&p_redirect=&p_lva=&p_ sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3J vd19jbnQ9Mjk2LDI5NiZwX3Byb2RzPTAmcF9jYXRzPTAmcF9wd j0mcF9jdj0mcF9zZWFyY2hfdHlwZT1hbnN3ZXJzLnNlYXJjaF9 mbmwmcF9wYWdlPTEmcF9zZWFyY2hfdGV4dD1zdXBwbGllZCBjY WJsZQ**&p_li=&p_topview=1
> and
> http://wdc.custhelp.com/cgi-bin/wdc.cfg/php/enduser/std_adp.php?p_faqid=1297&p_created=1102368573&p_si d=cVO3XkWi&p_accessibility=0&p_redirect=&p_lva=&p_ sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3J vd19jbnQ9Mjk2LDI5NiZwX3Byb2RzPTAmcF9jYXRzPTAmcF9wd j0mcF9jdj0mcF9zZWFyY2hfdHlwZT1hbnN3ZXJzLnNlYXJjaF9 mbmwmcF9wYWdlPTEmcF9zZWFyY2hfdGV4dD1zdXBwbGllZCBjY WJsZQ**&p_li=&p_topview=1
----
the cable that they suggested not to use was a specific type of cable
that doesn't use normal shielding.

But thanks...you did find a cable that didn't work properly. What do you
suppose was the problem with the cable that didn't work properly?

Craig

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Old 01-21-2008, 11:23 PM
Ed Greshko
 
Default HELP: External 250G USB screwed with GParted

Craig White wrote:

On Mon, 2008-01-21 at 15:22 -0500, Lamar Owen wrote:

On Monday 21 January 2008, Craig White wrote:

The guy from tech
support told me that he was unconcerned and that if the cable appeared
to be undamaged, it in all likelihood wasn't the problem and that in his
view, all commercially available USB device cables (6 foot and less)
were suitable for using with their USB 2.0 drives.
I have seen nothing to disprove that statement, either from my own
experience nor even the anecdotal experience of others. Only Tim's
theories and Tim is long on theories.


There was a slip of paper in the box with my 80GB WD PassPort drive that
warned to always use the supplied cable, and that the drive might not work
with other cables, and to not use extensions. My own experience trying to
use another cable, one that was the same length but had been supplied with a
USB multi-card reader (SanDisk branded), indicated that this was in fact
true, as the PassPort did not spin up with the SanDisk USB 2.0 cable, but
would with the supplied WD cable.


Please see
http://wdc.custhelp.com/cgi-bin/wdc.cfg/php/enduser/std_adp.php?p_faqid=1336&p_created=1112290978&p_si d=cVO3XkWi&p_accessibility=0&p_redirect=&p_lva=&p_ sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3J vd19jbnQ9Mjk2LDI5NiZwX3Byb2RzPTAmcF9jYXRzPTAmcF9wd j0mcF9jdj0mcF9zZWFyY2hfdHlwZT1hbnN3ZXJzLnNlYXJjaF9 mbmwmcF9wYWdlPTEmcF9zZWFyY2hfdGV4dD1zdXBwbGllZCBjY WJsZQ**&p_li=&p_topview=1
and
http://wdc.custhelp.com/cgi-bin/wdc.cfg/php/enduser/std_adp.php?p_faqid=1297&p_created=1102368573&p_si d=cVO3XkWi&p_accessibility=0&p_redirect=&p_lva=&p_ sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3J vd19jbnQ9Mjk2LDI5NiZwX3Byb2RzPTAmcF9jYXRzPTAmcF9wd j0mcF9jdj0mcF9zZWFyY2hfdHlwZT1hbnN3ZXJzLnNlYXJjaF9 mbmwmcF9wYWdlPTEmcF9zZWFyY2hfdGV4dD1zdXBwbGllZCBjY WJsZQ**&p_li=&p_topview=1

----
the cable that they suggested not to use was a specific type of cable
that doesn't use normal shielding.

But thanks...you did find a cable that didn't work properly. What do you
suppose was the problem with the cable that didn't work properly?


Gee....are you saying "Tim was right"?

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Old 01-22-2008, 12:02 AM
John Summerfield
 
Default HELP: External 250G USB screwed with GParted

Lamar Owen wrote:

There was a slip of paper in the box with my 80GB WD PassPort drive that
warned to always use the supplied cable, and that the drive might not work
with other cables, and to not use extensions. My own experience trying to
use another cable, one that was the same length but had been supplied with a
USB multi-card reader (SanDisk branded), indicated that this was in fact
true, as the PassPort did not spin up with the SanDisk USB 2.0 cable, but
would with the supplied WD cable.


Please see
http://wdc.custhelp.com/cgi-bin/wdc.cfg/php/enduser/std_adp.php?p_faqid=1336&p_created=1112290978&p_si d=cVO3XkWi&p_accessibility=0&p_redirect=&p_lva=&p_ sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3J vd19jbnQ9Mjk2LDI5NiZwX3Byb2RzPTAmcF9jYXRzPTAmcF9wd j0mcF9jdj0mcF9zZWFyY2hfdHlwZT1hbnN3ZXJzLnNlYXJjaF9 mbmwmcF9wYWdlPTEmcF9zZWFyY2hfdGV4dD1zdXBwbGllZCBjY WJsZQ**&p_li=&p_topview=1
and
http://wdc.custhelp.com/cgi-bin/wdc.cfg/php/enduser/std_adp.php?p_faqid=1297&p_created=1102368573&p_si d=cVO3XkWi&p_accessibility=0&p_redirect=&p_lva=&p_ sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3J vd19jbnQ9Mjk2LDI5NiZwX3Byb2RzPTAmcF9jYXRzPTAmcF9wd j0mcF9jdj0mcF9zZWFyY2hfdHlwZT1hbnN3ZXJzLnNlYXJjaF9 mbmwmcF9wYWdlPTEmcF9zZWFyY2hfdGV4dD1zdXBwbGllZCBjY WJsZQ**&p_li=&p_topview=1


I would be pretty seriously peeved at such a note. Use of USB logos and
assertions of standards compliance on the packaging mean that the device
is supposed to be interoperable with other devices meeting those
USB2.0standards.


If it requires the vendor-supplied cable, then the device is not USB2.0
compliant.


I have just identified a cable amongst my collection that does not seem
to be a USB2.0 cable, the hard drive I was using through it seemed to
run about 1 Mbytes/sec; I changed to another cable and got my 20+. In my
case, the cable's probably several years old, I remember buying one -
shielded with clear plastic coating - a while ago, to connect a printer.


--

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John

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Old 01-22-2008, 12:17 AM
Les
 
Default HELP: External 250G USB screwed with GParted

On Mon, 2008-01-21 at 23:51 +0800, Ed Greshko wrote:
> Craig White wrote:
> > On Mon, 2008-01-21 at 16:16 +0800, Ed Greshko wrote:
> >
> >> Craig White wrote:
> >>
> >>> On Mon, 2008-01-21 at 16:02 +1030, Tim wrote:
> >>>
> >>>
> >>>> Do you realise how stupid it is to even ask that? How many hundreds of
> >>>> brands may be available for purchase? How many different brands in
> >>>> different places that aren't available at the other places? How many
> >>>> that are fine, but aren't mentioned by someone, so people won't buy
> >>>> them? How many of the same product are sold by different labels? How
> >>>> many of different products are sold under the same label?
> >>>>
> >>>>
> >>> ----
> >>> I was hoping that you could name just one commercially available USB
> >>> cable that was not usable for USB 2.0
> >>>
> >>> Craig
> >>>
> >>>
> >> Somehow I can't imagine how unimportant that question is.... But, if
> >> you want me to pick you up a few of them from the cheap computer swap
> >> shops here in Taipei I'll get a few and send them to you. While I'm at
> >> it, I'll even get you some cheap CDs or DVDs that produce coasters 5-10%
> >> of the time.
> >>
> > ----
> > I've made my share of coasters but that is an entirely separate topic.
> >
> No, it isn't.
>
> There are substandard products everywhere one looks. And there are
> products that were built to satisfy a given standard but don't pass
> muster when the standard is updated. You just seem bent on trying to
> have Tim name a given product that will work on USB 1.0 but won't work
> on USB 2.0. Frankly, it is boring.
>
> I don't doubt that there are cables out there that work perfectly well
> with USB 1.0 and fail with USB 2.0. Just like I don't doubt that there
> are 10BaseT cables that work just fine at 10Mbps and not so good at
> 100Mbps....because I have experienced that end of the spectrum. But, I
> don't have to see them and touch them to know they exist.
>
> They exist. And, frankly, having been on the hardware end of
> manufacturing super computers, I could tell you some wonderful stories
> about coaxial cables used in the Control Data Cyber 205. But, you
> probably won't believe me either.
>
> Oh, that that "supervisor" that wasn't concerned or wouldn't even
> consider a cable problem is just plan...well how can I put
> it...ahhh....wrong.
>
> But, tell you what....you can go on believing what you will.
>
> But, it is truly unimportant why you are trying to "prove". So,
> whatever.....
>
I'm no engineer, but I do have over 40 years experience with RF,
including precision RF measurement (I was a calibration technician in
the US Navy.) I can assure you that Tim and Ed are both correct.
Cables do indeed affect signals, especially when you go above 50MHz, and
with digital signals such as USB, the total bandwidth necessary for good
signal fidelity is 10x the base rate. In otherwords for you cable to
work correctly for USB 2.0 its bandwidth would have to be nearly 5Ghz.
If it were for example only 4Ghz, you would have occasional dropouts of
single bit signals. Thus 110011 or 11100111 would transfer correctly,
while 10111 or 000100 would not. This leads to intermittant operation.
It is further compounded if the standard has signal encoding used to
reduce the total bandwidth consumption, because then the occasions for
single bit issues would be far rarer, but not eliminated. In otherwords
if the signal is known to be ascii text, the text could be encoded such
that vowel consonent pairs would produce lower frequencies, effectively
increasing the cables reliability without affecting bandwidth.

There are a number of papers detailing the issues involved, and if you
are really interested, I am sure all of us could point to some LaPlace
documentation or Fourier documentation, or even Karl could point you to
some papers and manuals for Amateur Radio, which would be lighter on
math, and heavier on text.

Regards,
Les H

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