Using --link-dest= multiple times - performance?

[Nico -telmich- Schottelius]

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/

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