Weird hanging problem with rsync

[Bauer, Georg]

Hi!

I have a weird problem I can't quite grasp. I rsync machines directories to
a central machine and backup from there to tape. So far so fine. But I have
weird hangings with rsync doing nothing whatsoever on some files. If this
situation arises, rsync won't go on with processing, won't actually work on
something (CPU is quite low in those situations) and will only send packages
over the wire very seldom - maybe once a minute or so. This most often
happens with logfiles like the syslog or the daemon.log - files that are
bound to change while they are rsynced. It happened with other files, too,
but those were allmost always active files or files in active directories
where current accesses change files.

So my questions is, is rsync actually capable of rsyncing files that change
while they are rsynced? Or if not, are there any tips on preventing this
weird hanging problem?

I use rsync versions 2.3 on debian potato and 2.5.5 (and 2.5.6 backported)
on debian 3.0. It even happens with to 2.5.6 versions combined and linked
directly without any proxy in between. rsync runs as rsync daemon on the
client machines and are pulled by the central backup system.

When I used it through a webproxy, the webproxy timeouted on those
situations and aborted the transfer (actually aborted the CONNECT session).
So I changed over to a directly routed solution, but now the command just
sits there and waits. Hint's would be highly appreciated, as currently our
backups are everything else than reliable :-(

bye, Georg