Re: "Using NFS over UDP on high-speed links such as Gigabit can cause silent data corruption."

[Harshula <harshula@redhat.com>]

On Tue, 2012-02-28 at 10:50 -0500, Chuck Lever wrote:
> On Feb 28, 2012, at 9:35 AM, Chuck Lever wrote:

> > My comment is that if the text in the TRANSPORT METHODS section in
> nfs(5) about UDP reassembly is not adequate it should be updated.  I
> would rather see the meat of the proposed text merged into that
> section; otherwise we have two disparate sections discussing the same
> topic.  That section is where this kind of discussion belongs.

Good point. I'll try to massage the text into that section.

> A few more comments.
> 
> Any file, including a /proc file, called out in new text should be
> added to the FILES section, IMO.
> 
> If we can't resolve the provenance issue, someone could rewrite the
> patch from scratch so that it addresses the review comments.

We now know who authored (Olaf Kirch) and committed (Mads Martin
Joergensen) the text at SUSE. Do we need to get a sign-off from someone
at SUSE?

> I don't agree with adding in-code warnings.  Mount works silently
> unless it fails, and this is not a mount failure.  Would such warnings
> ever be seen for NFS mounts added to /etc/fstab, or performed by
> automounter?  I think by and large most people type "mount -t nfs"
> without options and will get our current default transport setting,
> which is TCP, or UDP if the server does not support TCP.  Isn't that
> adequate?
> 
> We also know that the risk of using UDP is mitigated by using jumbo
> frames, specifying a small r/wsize, or by reducing the fragment
> reassembly timeout.  If an admin does those things, she still gets the
> warning.
> 
> It seems needlessly alarmist, and useless for our most common use
> cases.

Sounds reasonable. Just the man page text then.

cya,
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