bug#69535: closed (Problem with copying an EXTREMELY large file - cmp finds a mismatch)

[GNU bug Tracking System]

Your message dated Fri, 8 Mar 2024 11:21:45 -0800
with message-id <2d1e63b4-0406-4e8d-a37c-4d459983d29b@cs.ucla.edu>
and subject line Re: bug#69535: update
has caused the debbugs.gnu.org bug report #69535,
regarding Problem with copying an EXTREMELY large file - cmp finds a mismatch
to be marked as done.

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69535: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=69535
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> --- Begin Message ---
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> Subject: 
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> Problem with copying an EXTREMELY large file - cmp finds a mismatch
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> Date: 
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> Sun, 3 Mar 2024 15:04:51 -0500
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> User-agent: 
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> Mozilla Thunderbird
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> I don't know whether the problem I've found is with cp or with cmp, so 
> I don't know whether to address this report to coreutils or diffutils. 
> If you think I've guessed wrong, please tell me so.
>
> I am trying to make a backup copy of a very large (40 Gigabyte) data 
> file - yes, I have plenty of disk space! :) It's a binary file, 200 
> byte fixed length records to be precise, not a text file. I have 
> downloaded, compiled and used the latest versions of cp and cmp and 
> the problem persists. My system is a 16-core AMD Ryzen desktop running 
> Linux Mint 21.3.
>
> The steps to reproduce the problem are simple, provided you have the 
> data file!
>
> I have a folder called original in the data directory. From a terminal 
> prompt, I run
>
> cp data.dat original
>
> this apparently completes correctly - at least, no error messages are seen
>
> I then run
>
> cmp -l data.dat original/data.dat
>
> and I get something around 100 bytes of differences. On the basis of 
> three attempted copy and comparison pairs, the addresses of these 
> differences vary, but they're always a single block of contiguous 
> locations, and always towards the end of the file (the last time, they 
> were in the 35,000,000,000s).
>
> I have run a fsck on the drive (a 14 TB Seagate connected to one of 
> the motherboard SATA ports) and no problems were found.
>
> Any advice, please? I'm close to the limits of my debugging knowledge.
>
> Please note that I have absolutely zero knowledge of the C language or 
> its derivatives. I'm a (retired) scientist turned database programmer, 
> I know Pascal, FORTRAN and SQL, and that's about it.
>
>
> Thanks,
>
> Brian.
>
>
>
> --- End Message ---
> --- Begin Message ---
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> Subject: 
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> Re: bug#69535: update
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> Date: 
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> Fri, 8 Mar 2024 11:21:45 -0800
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> User-agent: 
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> Mozilla Thunderbird
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> On 2024-03-08 00:49, brian wrote:
> > Please consider this bug report to be closed. I'm not sure if/how I can 
> > do that via e-mail.
>
> Thanks for following up, and good luck with your hardware or drivers. 
> Closing the bug report.
>
>
> --- End Message ---