From: bfields@fieldses.org (J. Bruce Fields)
To: James Pearson <jcpearson@gmail.com>
Cc: linux-nfs@vger.kernel.org
Subject: Re: nfsd thread limit and UDP ?
Date: Wed, 20 Feb 2019 23:18:20 -0500 [thread overview]
Message-ID: <20190221041820.GA4625@fieldses.org> (raw)
In-Reply-To: <CAK3fRr9EL-YOp3yUr5tMe5zuiERxHjkLDhAaWkxxEHjtfSwisQ@mail.gmail.com>
On Wed, Feb 20, 2019 at 11:28:53AM +0000, James Pearson wrote:
> On a very busy NFSv3 server (running CentOS 6), we recently upped the
> nfsd thread count to 1024 - but this caused client mount requests over
> UDP to fail.
>
> We configure all our clients to use TCP for NFS mounts, but the
> automounter (automountd) on MacOS (up to version MacOS 10.12) seeds a
> 'null call' to the NFS server over UDP before attempting the mount -
> but the server appears to ignore any UDP requests - and the automount
> fails
By the way, you might also just turn off UDP. (Start run rpc.nfsd with
the -U option.) Hopefully MacOS can handle that case.
--b.
>
> I can also reproduce the issue on a Linux client via:
>
> mount -o udp,nfsvers=3 server:/export /mount/point
>
> I've found, by trial and error, that the maximum number of nfsd
> threads that can be run on the server is 1017 before UDP mount
> requests fail
>
> Running tcpdump on the server shows the UDP requests from the client,
> but the server never replies
>
> It looks like more recent versions of MacOS will do its test 'null
> call' over TCP - so that is one 'solution' to this issue
>
> However, I'm interested to know if we're hitting some hard limit, or
> if there are any settings we can tweak that could mitigate the
> problem?
>
> Thanks
>
> James Pearson
next prev parent reply other threads:[~2019-02-21 4:18 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-20 11:28 nfsd thread limit and UDP ? James Pearson
2019-02-20 17:44 ` J. Bruce Fields
2019-02-20 18:15 ` J. Bruce Fields
2019-02-21 4:18 ` J. Bruce Fields [this message]
2019-02-21 12:35 ` James Pearson
2019-02-21 15:20 ` J. Bruce Fields
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