2009-03-20 18:50:26

by Muntz, Daniel

[permalink] [raw]
Subject: RE: The next step: nfsvers=4



> -----Original Message-----
> From: Steve Dickson [mailto:[email protected]]
> Sent: Friday, March 20, 2009 4:50 AM
> To: Chuck Lever
> Cc: Benny Halevy; Linux NFS Mailing List
> Subject: Re: The next step: nfsvers=4
>
> Chuck Lever wrote:
> > If no vers= is specified and only NFSv4 is available on the server,
> > but something like "nocto" shows up on the command line
> mount options, do we:
> >
> > a) fail the mount, or
> > b) ignore the nocto option
> I would say ignore this particular option... since, in a
> sense, v4 give you this option by default due to
> delegations... but point well taken... The mapping of
> v3 to v4 and visa versa will have to be addressed... I would
> guess in the mount command...
>
> >
> > a) seems like the least surprising behavior.
> >
> > What about "proto=udp" ? Linux supports UDP for NFSv4,
> though other
> > server implementations probably don't. If that's specified
> on a mount
> > command line without a vers= option, what version should we choose?
> I think people just want things to work... so if they specify
> only UDP and the server supports V4, we give them V4/TCP. If
> they REALLY want UDP, they would have to specify 'nfsvers=3,udp'.

But, and this is a poor example, they REALLY want v4 and UDP? There
should be consistency in the way rules are applied. If specifying
vers=x requires the mount to match version x exactly, then imho, proto=y
should only succeed with protocol y. There should be a way for the user
to specify exactly what they want, and fail if they can't have it.
Similarly, if someone specifies sec=krb5p, you wouldn't want to fall
back to sec=sys :-)

>
> Or, if there was an mount configuration file, they could
> specify the MAX_VERSION to be 3 and then -o udp mounts work
> as expected...
>
> >
> >> For implementing more complex policies, maybe we can extend the
> >> command syntax to accept a range and/or an ordered list of
> versions
> >> to try.
> >
> > Steve mentioned /etc/default/nfs on Solaris. I could see
> > /etc/sysconfig/nfs on Linux containing a couple of lines
> defining the
> > range of allowable NFS versions, if we think this is
> necessary. This
> > is a simple pre-existing file, and has little potential for
> > introducing negative side-effects.
> The /etc/sysconfig/nfs is a distro only file... Meaning I
> know of only one distro that uses that file.. So I would tend
> to shy away from putting anything in that...
>
> steved.
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