Feature I'd love to see: --move-dest

[Josh Hanson]

David,

You make some good points. However, I still think a --move-dest feature would be handy. 

First of all, --link-dest is nice on platforms and file systems that support hard links, but not all platforms and file systems do, and some that do have tagged them on as an afterthought but don't support them very well, or very efficiently.

Second, even on systems that do support it, for frequent backups of large numbers of files which may change only rarely, the size of all the hard links may not be negligible.

Finally, it's always nice, given the option, to avoid hard links and keep a one-to-one relationship between the "files" I see (i.e. the links) and the actual allocated regions on the disk. Hard links make it impossible to know just how much space each backup takes up. If my backup disk is filling up, I'd like to be able to see which files are taking the most space; I might decide to manually delete older copies of large files, and I won't want to go through and delete every single link to the file.

-- Josh



-----Original Message-----
From: overton.d at googlemail.com [mailto:overton.d at googlemail.com] On Behalf Of David Overton
Sent: Monday, December 08, 2008 5:35 PM
To: Josh Hanson
Cc: rsync at lists.samba.org
Subject: Re: Feature I'd love to see: --move-dest

Hi,

I'm curious as to why you need a new option rather than just using
--link-dest.  Both --link-dest and --copy-dest already allow the "two
very common restor scenarios" that you mention and --link-dest uses
hardly any extra disk space than your --move-dest suggestion.  You
also get the added advantage that each previous backup continues to
look like a full "snapshot".

David

2008/12/9 Josh Hanson <JoshHanson at capriomgt.com>:
> Looking over rsync's --compare-dest, --copy-dest, and --link-dest
> options, there's one thing I really wish I could do, and I've been
> looking for a few years now for a program that could do it: Instead of
> copying or hard-linking from the compare directory to the target
> directory, I'd like to move the files.
>
> That is, whenever the file already exists in the compare directory, it
> is moved forward into the target directory; but if the existing file is
> different or doesn't exist, then a new file is made in the target
> directory.
>
> The result would be that, after several backups (each to a new
> directory, perhaps named with the current date) the most recent
> directory would be a snapshot of the source, and each previous directory
> would have previous versions of files or copies of deleted files. (This
> is effectively the opposite result of --compare-dest, which gives you a
> snapshot of the first version of the files, with each successive
> directory storing only the changed files.) This makes two very common
> restore scenarios very simple: restoring the entire directory tree to
> the most recent version after a drive failure, and restoring a previous
> version of a single file after it was accidentally over-written, even if
> the modified version has since been backed up.
>
> I looked over the rsync source to see if I could add this functionality
> myself, but I'm really not a very good programmer and it's definitely
> beyond me. To someone familiar with the source, however, I have to
> imagine it would be a fairly straightforward feature to add... just add
> replace the copy operation in --copy-dest or the link operation in
> --link-dest with a move operation.
>
> -- Josh
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