bug#38186: closed (dd doesn't copy whole file when specifying units with bs)

[GNU bug Tracking System]

Your message dated Wed, 13 Nov 2019 11:17:43 -0500 (EST)
with message-id <address@hidden>
and subject line Re: bug#38186: dd doesn't copy whole file when specifying 
units with bs
has caused the debbugs.gnu.org bug report #38186,
regarding dd doesn't copy whole file when specifying units with bs
to be marked as done.

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-- 
38186: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=38186
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> --- Begin Message ---
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> Subject: 
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> dd doesn't copy whole file when specifying units with bs
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> Date: 
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> Tue, 12 Nov 2019 15:47:19 -0500 (EST)
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> User-agent: 
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> Alpine 2.20 (DEB 67 2015-01-07)
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> Hi Guix,
>
> It seems that my version of dd from coreutils-8.31 does not seem to work 
> correctly when using units with the bs option (e.g. bs=1M). In the 
> terminal session below, I first use bs=1M. The output looks okay: dd 
> appears to have copied the whole 2.3GiB file, but it has done so 
> impossibly quickly. It turns out that went so quickly because the whole 
> file has not been copied. If instead of using the units modifier, I 
> specify the same number of bytes directly, everything seems to work as 
> expected (notice the slower speed).
>
> I have not determined whether this problem is specific to Guix.
>
> ```
> $ sudo dd if=image.iso of=/dev/sda bs=1M
> 2349+1 records in
> 2349+1 records out
> 2463842304 bytes (2.5 GB, 2.3 GiB) copied, 1.0693 s, 2.3 GB/s
> $ sudo dd if=image.iso of=/dev/sda bs=1048576
> 2349+1 records in
> 2349+1 records out
> 2463842304 bytes (2.5 GB, 2.3 GiB) copied, 3.03265 s, 812 MB/s
> $ ls -l /run/current-system/profile/bin/dd
> lrwxrwxrwx 18 root root 65 Dec 31  1969 /run/current-system/profile/bin/dd 
> -> /gnu/store/9kzrrccpzl6i1sfwb0drb00gi2gwk0x0-coreutils-8.31/bin/dd
> $ guix describe
> Generation 42   Oct 28 2019 11:51:58    (current)
>   guix 8c8d607
>     repository URL: https://git.savannah.gnu.org/git/guix.git
>     branch: master
>     commit: 8c8d60752e1ad73d5bd87d8497b357f8a8a389ab
> ```
>
> Best,
> Jack
>
>
>
> --- End Message ---
> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#38186: dd doesn't copy whole file when specifying units with bs
>
>
>
>
> Date: 
>
> Wed, 13 Nov 2019 11:17:43 -0500 (EST)
>
>
>
>
> User-agent: 
>
> Alpine 2.20 (DEB 67 2015-01-07)
>
>
>
>
> On Tue, 12 Nov 2019, Clément Lassieur wrote:
>
> > Does this[1] help?
> >
> > [1]: 
> > https://superuser.com/questions/730801/dd-immidiately-completes-but-actually-needs-sync
>
> Indeed it does. I guess I just got lucky with the second invocation that 
> data got written out. Thanks very much for the pointer, and sorry for the 
> extra noise.
>
> Since I no longer believe this to be a bug, I'm closing it.
>
> Best,
> Jack
>
> --- End Message ---