Re: nfs tranfers hang in state getblck or nfsread

From: Jason Stone <freebsd-current_at_dfmm.org>
Date: Thu, 28 Aug 2003 05:57:00 -0700 (PDT)
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> > I'm also seeing a similar problem - I have a cluster of high-volume
> > mailservers delivering mail over nfs to maildirs on a netapp.  The cluster
> > was all 4-stable, but I decided to mix a couple of 5.1 boxes in to see how
> > they would do.
[...]
> > My mounts are all nfsv3 over udp.
>
> UDP has problems, if you lose any packets at all.  The problem is that
> the packet reassembly buffer stays full until you retry, and the retry
> is out of band, for packets larger than the MTU size.
>
> What happens when you drop the read and write size low enough that the
> data and headers fit in a single UDP packet (e.g. according to
> "tcpdump")?  Does it "suddenly" become more reliable?

I'll try to play around with it and see.

We actually had this discussion already over on -performance (and I get
what you're saying), but the interesting question here is, why is 5.1
behaving so differently from 4-stable on identical hardware under
identical load.


 -Jason

 --------------------------------------------------------------------------
 Freud himself was a bit of a cold fish, and one cannot avoid the suspicion
 that he was insufficiently fondled when he was an infant.
	-- Ashley Montagu
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Received on Thu Aug 28 2003 - 03:57:02 UTC

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