* bug#38186: dd doesn't copy whole file when specifying units with bs
@ 2019-11-12 20:47 Jack Hill
2019-11-12 21:45 ` Clément Lassieur
0 siblings, 1 reply; 4+ messages in thread
From: Jack Hill @ 2019-11-12 20:47 UTC (permalink / raw)
To: 38186
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
^ permalink raw reply [flat|nested] 4+ messages in thread* bug#38186: dd doesn't copy whole file when specifying units with bs 2019-11-12 20:47 bug#38186: dd doesn't copy whole file when specifying units with bs Jack Hill @ 2019-11-12 21:45 ` Clément Lassieur 2019-11-13 16:17 ` Jack Hill 0 siblings, 1 reply; 4+ messages in thread From: Clément Lassieur @ 2019-11-12 21:45 UTC (permalink / raw) To: Jack Hill; +Cc: 38186 Hi Jack, > 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). Does this[1] help? [1]: https://superuser.com/questions/730801/dd-immidiately-completes-but-actually-needs-sync ^ permalink raw reply [flat|nested] 4+ messages in thread
* bug#38186: dd doesn't copy whole file when specifying units with bs 2019-11-12 21:45 ` Clément Lassieur @ 2019-11-13 16:17 ` Jack Hill 2019-11-13 17:00 ` Clément Lassieur 0 siblings, 1 reply; 4+ messages in thread From: Jack Hill @ 2019-11-13 16:17 UTC (permalink / raw) To: Clément Lassieur; +Cc: 38186-done [-- Attachment #1: Type: text/plain, Size: 399 bytes --] 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 ^ permalink raw reply [flat|nested] 4+ messages in thread
* bug#38186: dd doesn't copy whole file when specifying units with bs 2019-11-13 16:17 ` Jack Hill @ 2019-11-13 17:00 ` Clément Lassieur 0 siblings, 0 replies; 4+ messages in thread From: Clément Lassieur @ 2019-11-13 17:00 UTC (permalink / raw) To: Jack Hill; +Cc: 38186-done Jack Hill <jackhill@jackhill.us> writes: > 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. You're welcome :) Clément ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-11-13 17:01 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2019-11-12 20:47 bug#38186: dd doesn't copy whole file when specifying units with bs Jack Hill 2019-11-12 21:45 ` Clément Lassieur 2019-11-13 16:17 ` Jack Hill 2019-11-13 17:00 ` Clément Lassieur
Code repositories for project(s) associated with this public inbox https://git.savannah.gnu.org/cgit/guix.git This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).