Date: Mon, 14 Sep 2009 08:58:33 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-current@freebsd.org Cc: freebsd-fs@freebsd.org, qing.li@bluecoat.com Subject: Re: NFS client defaults to a mix of UDP and TCP Message-ID: <200909140858.34592.jhb@freebsd.org> In-Reply-To: <Pine.GSO.4.63.0909131356020.12138@muncher.cs.uoguelph.ca> References: <Pine.GSO.4.63.0909131356020.12138@muncher.cs.uoguelph.ca>
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On Sunday 13 September 2009 2:18:25 pm Rick Macklem wrote: > I had thought that I had posted w.r.t. before, but can't find it in > the archive (which might explain why I didn't get any responses:-). > > The current mount_nfs defaults to using UDP for the mount protocol > and then switches to using TCP for the actual mount. (When neither > "udp" nor "tcp" mount options are specified.) I don't think I > changed it to be this way, because I recall noticing it when I > added changes for the experimental NFS client and thought it was > "weird", but assumed that it had been that way for a long time. > > It now appears that it was introduced post-FreeBSD7 at r176198, > which changed the default for NFS to TCP, but didn't switch the > default for the mount protocol to TCP. > > The ancient history of this is that "once upon a time" there were > NFS servers that could do NFS over TCP, but only supported UDP for > the mount protocol and there was an option called "mntudp" for that > case. I can't imagine that any server still needs this case, but > it appears to have become the default. > > The default works fine for servers that support both UDP and TCP, > but result in a non-functional mount point when the server only > supports UDP. (See recent email thread on freebsd-stable called > "NFS issues on 8.0-BETA4".) > > Is this something that should be changed? rick Yes. I know of folks would love to have NFS use only TCP, including the initial RPC portmapper requests. IMO an NFS mount should use TCP for everything and a UDP mount should use UDP for everything by default. -- John Baldwin
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