--recursive and -H

[Matthias Schniedermeyer]

On 26.06.2010 21:27, Rob Thompson wrote:

> Aaah, thanks for the insight.  RSYNC must transfer the file regardless 
> of the link count, but it also takes note of the missing link.  So, it 
> probably considers an inode with multiple links "resolved" only after 
> it finds a brother/sister link and deletes the duplicate.

Yes and no. It is resolved when link-count amount of files have been 
encountered. No deleting involved as rsync can't infere that, as another 
hard-link can always be in a directory outside your transfer-directory.

And btw. without "--inplace" rsync will create a new file and hard-links 
that, when the file differs in source/target. IOW It breaks an existing 
hard-link on the target-site in regard to a hard-link outside the target 
dir.


> This would be consistent w/ the man page:
> 
> "-H, --hard-links
> ...
> If incremental recursion is active (see --recursive), rsync may transfer a missing hard-linked file before it finds that another link for that contents exists elsewhere in the hierarchy. This does not affect the accuracy of the transfer, just its efficiency"
> 
> Big props to those who code RSYNC, this stuff gets crazy ;)

Definitly. ;-)

> ----- "Matthias Schniedermeyer" <ms at citd.de> wrote:
> 
> > On 26.06.2010 09:01, Rob Thompson wrote:
> > > 
> > > Hello,
> > > 
> > > I have a question regarding using the --recursive option when 
> > > preserving hard link with -H.  How is it, that these two options are
> > 
> > > compatible when used together?  I would think that RSYNC would need
> > to 
> > > see all files/inodes before transferring, to preserve hard links. 
> > But 
> > > yet it still starts transferring before reading the entire file
> > list.
> > 
> > That's easy.
> > 
> > 'stat'ing a file also gives it's inode-number and the link-count
> > (number 
> > of directory entries).
> > 
> > When you have link-count == 1 there is nothing special to do.
> > 
> > When you have a link-count > 1 you can discard the data as soon as you
> > 
> > transferred as many files, with the same inode, as the link-count
> > says. 
> > Of course the discarding only works as long as all hard-links are
> > inside 
> > the directory-subtree you are transfering, otherwise rsync keeps
> > piling 
> > up memory, at least i'm pretty sure that rsync works that way.

-- 




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