rsync - Dec 2014 - Re[2]: --link-dest --inplace updates files without unlinking. What to do?

>- --inplace and --append-verify are essentially irrelevant when
>- --link-dest is in play.  With --link-dest in play the target system
>must write an entirely new file even for a change in permissions or
>timestamps so any potential benefit by these options are out the
>window from the start.  The only thing they can do is add the
>possibility of incomplete or corrupt copies on the target.
Okey, so, I should remove --inplace and --append-verify? But then copying large
file over unstable inet will not work, right? Is there any way to keep
--link-dest working right and simultaneously have possibility to copy large file
over unstable inet?
=Askar Safin
http://vk.com/safinaskar
Kazan, Russia

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Yes, but there are issues to keep in mind...

Normally --link-dest is used to keep previous copies (to make a backup
system) and the target directory is always empty.  In this mode
- --inplace and --append-verify would be irrelevant since rsync will
always be either making a link or writing an entire new file.

However, if you have an unstable link you might be using the same
target directory until it completes.  In this case --inplace and/or
- --append-verify would matter on files that already exist in the target
but are different than the source.

If you are doing the latter there is a huge gotcha you need to be
aware of...

When using --link-dest and the target directory is not empty then
rsync can "update" links within the target.  This means that if you
have a partially completed target and you run rsync again against it
it will complete the directory but if a file that has already been
linked into the directory has a metadata change that change will be
propagated to all instances of that file rather than making a new one
with the new metadata.

I want my metadata to be correct on each backup so if one of my
- --link-dest backups fails for some reason I delete the entire target
and start over using the same link-dest and a new empty target.

On 12/26/2014 08:24 AM, Askar Safin wrote:
>> - --inplace and --append-verify are essentially irrelevant when -
>> --link-dest is in play.  With --link-dest in play the target
>> system must write an entirely new file even for a change in
>> permissions or timestamps so any potential benefit by these
>> options are out the window from the start.  The only thing they
>> can do is add the possibility of incomplete or corrupt copies on
>> the target.
> Okey, so, I should remove --inplace and --append-verify? But then
> copying large file over unstable inet will not work, right? Is
> there any way to keep --link-dest working right and simultaneously
> have possibility to copy large file over unstable inet? == Askar
> Safin http://vk.com/safinaskar Kazan, Russia
> 
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Ok, thanks. I removed --inplace and --append-verify and kept --link-dest and
--partial.
And now the script works exactly as I want: hard-links are not updated, the
script is still robust and can
copy large files over unstable links etc, etc.
=Askar Safin
http://vk.com/safinaskar
Kazan, Russia