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Data transferred via USB ports is broken

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  Data transferred via USB ports is broken Stefan Mueller <seekware@yahoo.com> - 2011-05-11 16:04 -0700
    Re: Data transferred via USB ports is broken Tom Cole <tacoleNOSPAM@yahoo.co.nz> - 2011-05-12 11:22 +1200
    Re: Data transferred via USB ports is broken Roger Mills <watt.tyler@gmail.com> - 2011-05-12 18:03 +0100
      Re: Data transferred via USB ports is broken "Anthony R. Gold" <not-for-mail@ahjg.co.uk> - 2011-05-13 23:23 -0400
        Re: Data transferred via USB ports is broken Roger Mills <watt.tyler@gmail.com> - 2011-05-14 20:57 +0100
          Re: Data transferred via USB ports is broken Stefan Mueller <seekware@yahoo.com> - 2011-05-14 15:41 -0700
            Re: Data transferred via USB ports is broken "Anthony R. Gold" <not-for-mail@ahjg.co.uk> - 2011-05-14 19:41 -0400
            Re: Data transferred via USB ports is broken "~misfit~" <sore_n_happy@nospamyahoo.com.au> - 2011-05-15 13:54 +1200
              Re: Data transferred via USB ports is broken "Anthony R. Gold" <not-for-mail@ahjg.co.uk> - 2011-05-14 22:47 -0400
                Re: Data transferred via USB ports is broken "Anthony R. Gold" <not-for-mail@ahjg.co.uk> - 2011-05-15 01:29 -0400
              Re: Data transferred via USB ports is broken Stefan Mueller <seekware@yahoo.com> - 2011-05-15 12:10 -0700
            Re: Data transferred via USB ports is broken lmarco@panix.com (Lou Marco) - 2011-05-17 17:01 +0000
              Re: Data transferred via USB ports is broken ak621@chebucto.ns.ca (Richard Bonner) - 2011-05-26 16:02 +0000
            Re: Data transferred via USB ports is broken ak621@chebucto.ns.ca (Richard Bonner) - 2011-05-26 15:57 +0000
    Re: Data transferred via USB ports is broken lmarco@panix.com (Lou Marco) - 2011-05-17 16:56 +0000

#191 — Data transferred via USB ports is broken

I've a Compaq Evo N800c laptop with a clean Windows XP installation.
If I copy a file via the onboard network adapter (Ethernet) and do
afterwards a compare of the original and the copied file both files
are identical. But if I do the same data transfer to an USB stick or
USB harddisk the copied files are not identical to the original files.
Because I thought it's a problem of the internal USB controller and/or
USB ports I bought an USB PCMCIA card which I can insert into the
laptop. Unfortunatelly also the copied files via the new USB card are
not identical to the original files.

Does someone have an idea what the problem could be and perhaps how it
could be fixed?

Regards
Stefan

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#192

On Wed, 11 May 2011 16:04:17 -0700 (PDT), Stefan Mueller
<seekware@yahoo.com> wrote:

>I've a Compaq Evo N800c laptop with a clean Windows XP installation.
>If I copy a file via the onboard network adapter (Ethernet) and do
>afterwards a compare of the original and the copied file both files
>are identical. But if I do the same data transfer to an USB stick or
>USB harddisk the copied files are not identical to the original files.
>Because I thought it's a problem of the internal USB controller and/or
>USB ports I bought an USB PCMCIA card which I can insert into the
>laptop. Unfortunatelly also the copied files via the new USB card are
>not identical to the original files.
>
>Does someone have an idea what the problem could be and perhaps how it
>could be fixed?
>
How are you determining that the copied files are not identical?  

Most USB sticks are formatted as FAT, and the timestamps of files in
this file system have an accuracy of up to +/-2 seconds. This will
affect files copied from an NTFS file system, which have much more
accurate timestamps.

If the comparison utility you're using is comparing timestamps without
allowing for this difference, then it will report that the files are
different, even though the data may be identical.

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#193

On 12/05/2011 00:04, Stefan Mueller wrote:
> I've a Compaq Evo N800c laptop with a clean Windows XP installation.
> If I copy a file via the onboard network adapter (Ethernet) and do
> afterwards a compare of the original and the copied file both files
> are identical. But if I do the same data transfer to an USB stick or
> USB harddisk the copied files are not identical to the original files.
> Because I thought it's a problem of the internal USB controller and/or
> USB ports I bought an USB PCMCIA card which I can insert into the
> laptop. Unfortunatelly also the copied files via the new USB card are
> not identical to the original files.
>
> Does someone have an idea what the problem could be and perhaps how it
> could be fixed?
>
> Regards
> Stefan

What method are you using to compare the files?

What happens when you copy:
a) between two different USB devices
b) from hard-disk to USB stick and then back to hard-disk?

The amount of disk space used will probably be different in different 
media because of differences in the format system and/or block size.

But it's almost certain that the actual *contents* of the files - as 
seen by the applications which use those files - will be the same.

I suspect that you are chasing a non-existent problem.
-- 
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom 
checked.

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#197

On Thu, 12 May 2011 18:03:03 +0100, Roger Mills <watt.tyler@gmail.com> wrote:

> What happens when you copy:
> a) between two different USB devices
> b) from hard-disk to USB stick and then back to hard-disk?
>
> The amount of disk space used will probably be different in different 
> media because of differences in the format system and/or block size.
>
> But it's almost certain that the actual *contents* of the files - as 
> seen by the applications which use those files - will be the same.

Back in the days of 8 bit CP/M that could have been true but Windows counts
file sizes to the exact byte and I have never even once seen something that
you claim to be "almost certain".

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#198

On 14/05/2011 04:23, Anthony R. Gold wrote:
> On Thu, 12 May 2011 18:03:03 +0100, Roger Mills<watt.tyler@gmail.com>  wrote:
>
>> What happens when you copy:
>> a) between two different USB devices
>> b) from hard-disk to USB stick and then back to hard-disk?
>>
>> The amount of disk space used will probably be different in different
>> media because of differences in the format system and/or block size.
>>
>> But it's almost certain that the actual *contents* of the files - as
>> seen by the applications which use those files - will be the same.
>
> Back in the days of 8 bit CP/M that could have been true but Windows counts
> file sizes to the exact byte and I have never even once seen something that
> you claim to be "almost certain".

As far as I know, the OP hasn't been back to tell us how he was 
comparing the files.

I was making the point that, in Windows, a file has *two* sizes - the 
number of bytes of contents and the number of bytes of disk space occupied.

If you copy a file from one storage device to another, the first of 
these should always be the same - but the second frequently won't 
because it will always be an integral number of blocks, and will thus 
change with blocksize.

I suspect that the OP's copy is ok (which is what I meant by saying that 
the contents will almost certainly be the same) and that he has been 
misled by some spurious comparison into thinking that he has a problem.
-- 
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom 
checked.

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#199

On May 14, 9:57 pm, Roger Mills <watt.ty...@gmail.com> wrote:
> On 14/05/2011 04:23, Anthony R. Gold wrote:
>
> > On Thu, 12 May 2011 18:03:03 +0100, Roger Mills<watt.ty...@gmail.com>  wrote:
>
> >> What happens when you copy:
> >> a) between two different USB devices
> >> b) from hard-disk to USB stick and then back to hard-disk?
>
> >> The amount of disk space used will probably be different in different
> >> media because of differences in the format system and/or block size.
>
> >> But it's almost certain that the actual *contents* of the files - as
> >> seen by the applications which use those files - will be the same.
>
> > Back in the days of 8 bit CP/M that could have been true but Windows counts
> > file sizes to the exact byte and I have never even once seen something that
> > you claim to be "almost certain".
>
> As far as I know, the OP hasn't been back to tell us how he was
> comparing the files.
>
> I was making the point that, in Windows, a file has *two* sizes - the
> number of bytes of contents and the number of bytes of disk space occupied.
>
> If you copy a file from one storage device to another, the first of
> these should always be the same - but the second frequently won't
> because it will always be an integral number of blocks, and will thus
> change with blocksize.
>
> I suspect that the OP's copy is ok (which is what I meant by saying that
> the contents will almost certainly be the same) and that he has been
> misled by some spurious comparison into thinking that he has a problem.
> --
> Cheers,
> Roger
> ____________
> Please reply to Newsgroup. Whilst email address is valid, it is seldom
> checked.


Thanks a lot for all your replies.
Unfortunately the copied files are really not identical. I do the
comparison with the 'comp' command from the Windows command prompt.
I realized the first time that there is a problem as I tried to open a
Ghost image which was copied before from my Compaq Evo N800c to my
external USB harddisk (drag and drop). The Ghost Explorer complained
that the image file is corrupted.
I think this problem occurs only while copying huge files and only
from time to time. But it's very uncomfortable if you can't be sure
that the files have been copied correctly.

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#200

On Sat, 14 May 2011 15:41:18 -0700 (PDT), Stefan Mueller <seekware@yahoo.com>
wrote:

> Thanks a lot for all your replies.
> Unfortunately the copied files are really not identical. I do the
> comparison with the 'comp' command from the Windows command prompt.
> I realized the first time that there is a problem as I tried to open a
> Ghost image which was copied before from my Compaq Evo N800c to my
> external USB harddisk (drag and drop). The Ghost Explorer complained
> that the image file is corrupted.
> I think this problem occurs only while copying huge files and only
> from time to time. But it's very uncomfortable if you can't be sure
> that the files have been copied correctly.

Speaking of Ghost, I found I could never get a verified image of the HDD in a
Shuttle computer using Drive Image v7, the program that Symantec bought from
PowerQuest as the basis for Ghost v9 and onwards, onto a USB attached
external drive Shuttle. There was an issue with the Shuttle motherboard's USB
port or its driver that I never solved. I never has that problem with any of
my Lenovo, IBM or HP/Compaq computers and I continue to use DIv7 to this day.

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#201

Somewhere on teh intarwebs Stefan Mueller wrote:
> On May 14, 9:57 pm, Roger Mills <watt.ty...@gmail.com> wrote:
>> On 14/05/2011 04:23, Anthony R. Gold wrote:
>>
>>> On Thu, 12 May 2011 18:03:03 +0100, Roger
>>> Mills<watt.ty...@gmail.com> wrote:
>>
>>>> What happens when you copy:
>>>> a) between two different USB devices
>>>> b) from hard-disk to USB stick and then back to hard-disk?
>>
>>>> The amount of disk space used will probably be different in
>>>> different media because of differences in the format system and/or
>>>> block size.
>>
>>>> But it's almost certain that the actual *contents* of the files -
>>>> as seen by the applications which use those files - will be the
>>>> same.
>>
>>> Back in the days of 8 bit CP/M that could have been true but
>>> Windows counts file sizes to the exact byte and I have never even
>>> once seen something that you claim to be "almost certain".
>>
>> As far as I know, the OP hasn't been back to tell us how he was
>> comparing the files.
>>
>> I was making the point that, in Windows, a file has *two* sizes - the
>> number of bytes of contents and the number of bytes of disk space
>> occupied.
>>
>> If you copy a file from one storage device to another, the first of
>> these should always be the same - but the second frequently won't
>> because it will always be an integral number of blocks, and will thus
>> change with blocksize.
>>
>> I suspect that the OP's copy is ok (which is what I meant by saying
>> that the contents will almost certainly be the same) and that he has
>> been misled by some spurious comparison into thinking that he has a
>> problem. --
>> Cheers,
>> Roger
>> ____________
>> Please reply to Newsgroup. Whilst email address is valid, it is
>> seldom checked.
>
>
> Thanks a lot for all your replies.
> Unfortunately the copied files are really not identical. I do the
> comparison with the 'comp' command from the Windows command prompt.
> I realized the first time that there is a problem as I tried to open a
> Ghost image which was copied before from my Compaq Evo N800c to my
> external USB harddisk (drag and drop). The Ghost Explorer complained
> that the image file is corrupted.
> I think this problem occurs only while copying huge files and only
> from time to time. But it's very uncomfortable if you can't be sure
> that the files have been copied correctly.

Is the USB device formatted FAT32? Could it be that you're running into the 
FAT32 file-size limit? (4GB)
-- 
Shaun.

"He who fights with monsters might take care lest he thereby become a
monster. And if you gaze for long into an abyss, the abyss gazes also
into you." Friedrich Wilhelm Nietzsche 

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#202

On Sun, 15 May 2011 13:54:53 +1200, "~misfit~"
<sore_n_happy@nospamyahoo.com.au> wrote:

> Somewhere on teh intarwebs Stefan Mueller wrote:
>> On May 14, 9:57 pm, Roger Mills <watt.ty...@gmail.com> wrote:
>>> On 14/05/2011 04:23, Anthony R. Gold wrote:
>>>
>>>> On Thu, 12 May 2011 18:03:03 +0100, Roger
>>>> Mills<watt.ty...@gmail.com> wrote:
>>>
>>>>> What happens when you copy:
>>>>> a) between two different USB devices
>>>>> b) from hard-disk to USB stick and then back to hard-disk?
>>>
>>>>> The amount of disk space used will probably be different in
>>>>> different media because of differences in the format system and/or
>>>>> block size.
>>>
>>>>> But it's almost certain that the actual *contents* of the files -
>>>>> as seen by the applications which use those files - will be the
>>>>> same.
>>>
>>>> Back in the days of 8 bit CP/M that could have been true but
>>>> Windows counts file sizes to the exact byte and I have never even
>>>> once seen something that you claim to be "almost certain".
>>>
>>> As far as I know, the OP hasn't been back to tell us how he was
>>> comparing the files.
>>>
>>> I was making the point that, in Windows, a file has *two* sizes - the
>>> number of bytes of contents and the number of bytes of disk space
>>> occupied.
>>>
>>> If you copy a file from one storage device to another, the first of
>>> these should always be the same - but the second frequently won't
>>> because it will always be an integral number of blocks, and will thus
>>> change with blocksize.
>>>
>>> I suspect that the OP's copy is ok (which is what I meant by saying
>>> that the contents will almost certainly be the same) and that he has
>>> been misled by some spurious comparison into thinking that he has a
>>> problem. --
>>> Cheers,
>>> Roger
>>> ____________
>>> Please reply to Newsgroup. Whilst email address is valid, it is
>>> seldom checked.
>>
>>
>> Thanks a lot for all your replies.
>> Unfortunately the copied files are really not identical. I do the
>> comparison with the 'comp' command from the Windows command prompt.
>> I realized the first time that there is a problem as I tried to open a
>> Ghost image which was copied before from my Compaq Evo N800c to my
>> external USB harddisk (drag and drop). The Ghost Explorer complained
>> that the image file is corrupted.
>> I think this problem occurs only while copying huge files and only
>> from time to time. But it's very uncomfortable if you can't be sure
>> that the files have been copied correctly.
>
> Is the USB device formatted FAT32? Could it be that you're running into the 
> FAT32 file-size limit? (4GB)

NTFS.

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#204

On Sat, 14 May 2011 22:47:52 -0400, "Anthony R. Gold"
<not-for-mail@ahjg.co.uk> wrote:

> On Sun, 15 May 2011 13:54:53 +1200, "~misfit~"
> <sore_n_happy@nospamyahoo.com.au> wrote:
>
>> Is the USB device formatted FAT32? Could it be that you're running into the 
>> FAT32 file-size limit? (4GB)
>
> NTFS.

Whoops, the tilde in your screen name misled me to believe you were replying
to me. Please ignore that post.

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#205

On May 15, 3:54 am, "~misfit~" <sore_n_ha...@nospamyahoo.com.au>
wrote:
> Somewhere on teh intarwebs Stefan Mueller wrote:
>
>
>
>
>
> > On May 14, 9:57 pm, Roger Mills <watt.ty...@gmail.com> wrote:
> >> On 14/05/2011 04:23, Anthony R. Gold wrote:
>
> >>> On Thu, 12 May 2011 18:03:03 +0100, Roger
> >>> Mills<watt.ty...@gmail.com> wrote:
>
> >>>> What happens when you copy:
> >>>> a) between two different USB devices
> >>>> b) from hard-disk to USB stick and then back to hard-disk?
>
> >>>> The amount of disk space used will probably be different in
> >>>> different media because of differences in the format system and/or
> >>>> block size.
>
> >>>> But it's almost certain that the actual *contents* of the files -
> >>>> as seen by the applications which use those files - will be the
> >>>> same.
>
> >>> Back in the days of 8 bit CP/M that could have been true but
> >>> Windows counts file sizes to the exact byte and I have never even
> >>> once seen something that you claim to be "almost certain".
>
> >> As far as I know, the OP hasn't been back to tell us how he was
> >> comparing the files.
>
> >> I was making the point that, in Windows, a file has *two* sizes - the
> >> number of bytes of contents and the number of bytes of disk space
> >> occupied.
>
> >> If you copy a file from one storage device to another, the first of
> >> these should always be the same - but the second frequently won't
> >> because it will always be an integral number of blocks, and will thus
> >> change with blocksize.
>
> >> I suspect that the OP's copy is ok (which is what I meant by saying
> >> that the contents will almost certainly be the same) and that he has
> >> been misled by some spurious comparison into thinking that he has a
> >> problem. --
> >> Cheers,
> >> Roger
> >> ____________
> >> Please reply to Newsgroup. Whilst email address is valid, it is
> >> seldom checked.
>
> > Thanks a lot for all your replies.
> > Unfortunately the copied files are really not identical. I do the
> > comparison with the 'comp' command from the Windows command prompt.
> > I realized the first time that there is a problem as I tried to open a
> > Ghost image which was copied before from my Compaq Evo N800c to my
> > external USB harddisk (drag and drop). The Ghost Explorer complained
> > that the image file is corrupted.
> > I think this problem occurs only while copying huge files and only
> > from time to time. But it's very uncomfortable if you can't be sure
> > that the files have been copied correctly.
>
> Is the USB device formatted FAT32? Could it be that you're running into the
> FAT32 file-size limit? (4GB)
> --
> Shaun.
>
> "He who fights with monsters might take care lest he thereby become a
> monster. And if you gaze for long into an abyss, the abyss gazes also
> into you." Friedrich Wilhelm Nietzsche- Hide quoted text -
>
> - Show quoted text -

No, my external 1.0 TB USB harddisk is formatted with NTFS.
I'm using the same USB harddisk with all my IBM ThinkPads (T21, T22,
T23, T30, A31p, T60p) and also with my Compaq Evo N600c without any
troubles.
Because I experience the mentioned problem only with my Compaq Evo
N800c I think it's a hardware problem what was the reason I bought an
USB PCMCIA card which I can insert into the
laptop. Unfortunatelly it didn't solve the problem. Now I'm lost.

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#214

In article <9c1535d8-1690-48b8-9122-d260416d69b4@s2g2000yql.googlegroups.com>,
Stefan Mueller  <seekware@yahoo.com> wrote:
>
>Thanks a lot for all your replies.
>Unfortunately the copied files are really not identical. I do the

	Comp isn't a very good way to compare files.  They have to be
exactly the same size for one thing.

	Sounds like you have a bad USB drive, though.

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#225

Lou Marco (lmarco@panix.com) wrote:
> 	Comp isn't a very good way to compare files.  They have to be
> exactly the same size for one thing.

***   He might try "FC.com" or "FC.exe" if CMD has it.

-- 
         Richard Bonner
http://www.chebucto.ca/~ak621/DOS/

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#224

Stefan Mueller (seekware@yahoo.com) wrote:
> Thanks a lot for all your replies.
> Unfortunately the copied files are really not identical. I do the
> comparison with the 'comp' command from the Windows command prompt.
(Snip)

> I think this problem occurs only while copying huge files and only
> from time to time. But it's very uncomfortable if you can't be sure
> that the files have been copied correctly.

***   I have not used Windows in some time, but try copying a test
file at the command line using XCOPY and its `/V' (Verify) switch to see
what that does. This won't check for file differences, but it will test
to see if the data can be read from the target drive. 

   To see if your XCOPY has this switch:

XCOPY /?

   For a more powerful XCOPY, get XXCOPY and use its `/V2' switch. This
will do a byte by byte check.

			http://www.xxcopy.com/

-- 
         Richard Bonner
http://www.chebucto.ca/~ak621/DOS/

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#213

In article <91146369-341d-4b1a-95b1-c907d1ee178b@z7g2000prh.googlegroups.com>,
Stefan Mueller  <seekware@yahoo.com> wrote:
>
>Does someone have an idea what the problem could be and perhaps how it
>could be fixed?
>

	It's harmless in all but esoteric circumstances.  A device doesn't
really move a file character by character.  And if it does, the disc drive 
doesn't save data that way.  What's probably happening is that the chunks 
(blocks) that the USB device is using are larger or smaller than the blocks
something else in the data path is using.  When you have to fit 3 20 byte
blocks into 1 51 byte block (for example) you take the 51 byte block,
make it into 3 20 byte blocks, and then pad (fill) the empty space with 0 bytes
(or whatever).

	The operating system knows where the file really ends so the "padding"
doesn't matter.  The program that says they're different is probably just
adding up the size of the allocated blocks (the blocks that have some part of
the file).

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