rsync - Aug 2007 - Using --link-dest= multiple times - performance?

Hello guys!

I'm thinking about using rsync with multiple times --link-dest= specified in
ccollect [0].

Now I'm wondering about the performance and memory usage:

- How much more memory will rsync use for every --link-dest= parameter?
- How heavy do you expect it to influence performance with every
  additional --link-dest= parameter?

In general I think that rsync could either

- use index_size memory for each --link-dest, doing full index of the
  directory
- or just do stat() for each file in the source in each directory
  specified by --link-dest 

As stats() in general are not that heavy I expect it not to cost much
additional time, but on the other hand, stat()ing 50k files will still
take some time.

I'm just interested in what your ideas / thoughts about that are. If
the cost of cpu/ram is not too much, I would like to make it the
standard in ccollect to --link-dest to all existing backups (which can
be quite many, depending on the configuration).

Sincerly

Nico

[0]: http://unix.schottelius.org/ccollect/

-- 
Think about Free and Open Source Software (FOSS).
http://nico.schottelius.org/documentations/foss/the-term-foss/

PGP: BFE4 C736 ABE5 406F 8F42  F7CF B8BE F92A 9885 188C
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: Digital signature
Url :
http://lists.samba.org/archive/rsync/attachments/20070820/c6f480e4/attachment.bin

On 8/20/07, Nico -telmich- Schottelius <nico-rsync@schottelius.org>
wrote:
> In general I think that rsync could either
[...]
> - or just do stat() for each file in the source in each directory
>   specified by --link-dest
This is what rsync currently does.*  Thus:
> - How much more memory will rsync use for every --link-dest= parameter?
Just enough memory to store the path of the --link-dest directory.

* And rather naively; see https://bugzilla.samba.org/show_bug.cgi?id=4037 .

Matt