Docs: detecting metadata changes

[Jori Mantysalo]

I just tested our backup system, that is done with rsync. When I changed 
metadata of file --- for example permissions --- rsync notices change and 
copies permissions to backup. However, our archiving does not work. So I 
can roll back to older contents of a file but not to older permissions, 
owner/group information etc.

Several web pages claim that rsync does not detect metadata changes at 
all. See for example http://www.noah.org/wiki/rsync_notes

I think that rsync FAQ or other documentation should cover this. 
Difference between mtime and ctime might not be that clear to all. Also 
there could be some note about "cp -u", because it is first thing to come 
in mind if somebody is setting up archiving backups.

-- 
Jori Mäntysalo