[Linux-cluster] Re: NFS relocate: old TCP/IP connection resulting in DUP/ACK storms and largish timeouts

[Axel Thimm]

On Mon, Sep 05, 2005 at 05:36:49PM +0200, Axel Thimm wrote:
> On Tue, Aug 30, 2005 at 02:03:32PM -0400, Lon Hohberger wrote:
> > On Tue, 2005-08-30 at 01:35 +0200, Axel Thimm wrote:
> > 
> > > > It's really an attempt at a workaround a configuration problem -- and
> > > > nothing more.
> > > 
> > > The above is with nfs running on all nodes already. The racing seems
> > > to be with the exportfs commands and ip setup/teardown.

> > ewww...  Can you bugzilla this so we can track it?  =)

> One bug that has critalled out is that upon relocation the old server
> keeps his TCP connections to the NFS client. When this server later on
> gets to become the NFS server again, he FIN/ACKs that old connection
> to the client (that had this connection torn down by now), which
> creates a DUP/ACK storm.
> 
> A workaround is to shutdown nfs instead of simply unexporting like
> nfsexport.sh does, so that the pending TCP connections get fried, too.
> 
> Is there a way to have ip.sh fry all open TCP/IP connections to a
> service IP that is to be abandoned? I guess that would be the better
> solution (that would also apply to non-NFS services).
> 
> Of course the true bug is the DUP/ACK storm that is triggered by the
> old open TCP connection.

Both bugs have been filed in bugzilla:

https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=167571
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=167572

I guess the latter will move to another component like "kernel", if it
really turns out to be neither cluster nor even nfs specific.
-- 
Axel.Thimm at ATrpms.net
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