On Tue, Sep 25, 2012 at 10:33 PM, Emmett Culley <emm...@webengineer.com> wrote:
> I have been using BackupPC via rsync daemons on the target machines and all
> has been working well. At least until about the time rsync went to version
> 3.0.6.
>
> Since then backups have been failing for some targets. The failure is a TCP
> ZeroWindow issue. It looks like the server rsync process cannot empty it's
> buffer soon enough and eventually the process fails.
>
> I really do not know if it is rsync version related, because I never looked
> at the packet stream until I started having failures.
>
> BackupPC was running on a VM host and the failing machine was one of the
> guest VMs. I tried upgrading rsync to 3.0.9 and that didn't help.
>
> So I moved the BackupPC set up to a different server (no VM). Not all
> backups are working. though I still see some ZeroWindow packets along with a
> few retransmision packets. But the backup completes on all machines,
> including the VM that was failing before.
>
> I've googled rsync zerowindow and found some references, but none seemed to
> apply to my situation.
>
> Anybody else having a similar experience?
I found an old mention of turning off TCP window scaling solving a
problem with rsync (not involving backuppc). Seems unlikely but
might be worth a try: sysctl -w net.ipv4.tcp_window_scaling=0.
--
Les Mikesell
lesmikes...@gmail.com
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