Hi Kevin,
The -a flag in this instance is not back-dating the timestamp of the copied
file to the source file. It is modifying it to the time of transfer and leaving
it that way. Then any time I rerun that command it always updates the timestamp
since it is always making it the time of transfer. I have a source file the has
a modification date of 2015 and when I rsync it to day with -a the copied file
has a modification date of today.
Again, this only happens on files that I use rsync to copy for the first time
over to empty storage. If I drag and drop the timestamp stays the same as the
source file and any rsync -a commands subsequently run do not modify the file
in any way. When I use rsync -a to copy over the first time, the timestamp is
modified to the current time and then continues to update anytime I run rsync -a
-Blake
From: rsync <rsync-boun...@lists.samba.org> on behalf of Kevin Korb via rsync
<rsync@lists.samba.org>
Date: Wednesday, October 9, 2024 at 14:45
To: rsync@lists.samba.org <rsync@lists.samba.org>
Subject: Re: Question About Rsync and Modification Times
External Email - Exercise Caution
You are using rsync -a which copies (preserves) the timestamp. Meaning
that rsync will copy the file then back-date it to the timestamp of the
source file. Most copying tools do not do this though cp's -a does it
too. Note that your itemized output says that the timestamp is
different meaning that the file has changed since rsync last ran.
Without the -a (or the included -t) the itemized output would have shown
a 'T' instead of a 't' meaning "The timestamp is different and I'm not
fixing it.".
If the file wasn't being modified the timestamp wouldn't be different
and rsync would have just skipped it.
On 10/9/24 14:06, McDowell, Blake via rsync wrote:
> Hello,
>
> I have a question about how/why rsync updates modification times, which
> I haven’t been able to find an answer to.
>
> I have two locally connected storage devices running TrueNAS Core: one
> is new and empty, while the other is filled with files.
>
> When I run the following rsync command:
>
> /rsync -avPh --itemize-changes --stats "${@}"/
>
> to transfer files from the full storage to the empty one, the
> modification times of the transferred files are updated to the time of
> transfer. I understand that using rsync to transfer to an empty storage
> may not offer any real advantage, and that the modification times are
> updated because rsync "touches" the files. However, I would prefer for
> rsync not to update the modification times, though I gather this might
> not be possible.
>
> For context, the /--itemize-changes/ output during the initial transfer
> looks like this:
>
> />f++++++++++/
>
> Now, if I wait for a minute and then run a dry run with the same command
> on the files I just transferred, the output changes to:
>
> />f..t......./
>
> If I actually rerun the command, rsync updates the modification times to
> the current time. This behavior repeats endlessly each time I run the
> command.
>
> Interestingly, if I manually "drag and drop" the files to the empty
> storage, the modification times remain the same as the original files,
> which is the outcome I prefer. Moreover, if I run the same rsync command
> (/rsync -avPh --itemize-changes --stats "${@}"/) on the files that I
> dragged and dropped, rsync doesn’t transfer or update any file, and the
> /--itemize-changes/ output looks like this:
>
> /.f/
>
> I’m puzzled as to why rsync behaves differently for files initially
> transferred using rsync versus those transferred via drag and drop.
> Could this behavior be more related to TrueNAS rather than rsync?
>
> Any clarification would be greatly appreciated.
>
> Thanks,
>
> Bleakley
>
>
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