[kwlug-disc] thoughts/observations/questions re: NFSv4

[Robert P. J. Day]

  by way of prepping for my upcoming novell CLP 11 practicum, i've
been messing with NFSv4 and there's definitely some confusion about
how it works depending on what you're reading, so here's hoping
someone out there can clear a bit of this up.

  first, is NFSv4 considered to be production ready?  as i read it,
version 4.1 is tagged as experimental, but v4 itself seems to be ready
for prime time.  is that correct?

  next (and my most important question), is it feasible to run NFS
*exclusively* using v4 (that is, with no support for earlier
versions)?  that assumes that there's actually a way to start NFS with
support for *only* the NFSv4 protocol and depending on your linux
distro, it might not be obvious how to do that.

  in fedora 12, the file /etc/sysconfig/nfs contains:

#MOUNTD_NFS_V1="no"
#MOUNTD_NFS_V2="no"
#MOUNTD_NFS_V3="no"

which makes it easy to just uncomment what versions you want to drop
WRT to the mount command. and further down, there's:

# Optional arguments passed to rpc.nfsd. See rpc.nfsd(8)
# Turn off v2 and v3 protocol support
#RPCNFSDARGS="-N 2 -N 3"
# Turn off v4 protocol support
#RPCNFSDARGS="-N 4"

again, looks easy.  under suse linux ES 11 (SLES 11), however, that
same file contains only:

NFS4_SUPPORT="yes"  (or "no")

which makes it not as obvious as to how to get NFSv4 support *while
dropping support for all earlier versions*.

  the way support is dropped is that both rpc.mountd and rpc.nfsd
support the option {-N, --no-nfs-version} 2, 3 or 4 so, no matter
what, you should be able to hack this.

  moving on, based on what i read here:

http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.4/html/Deployment_Guide/ch-nfs.html

it appears that NFSv4 no longer needs to communicate with
portmapper/rpcbind, rpc.mountd or rpc.statd.  i've heard two different
descriptions of what that means:

1) rpc.mountd and rpc.statd don't even need to be running anymore, or

2) they need to be running but only available on the local server --
they need not be accessible from remote systems so you don't need to
open the firewall for them.

  i'm sure i'm forgetting some stuff, but can anyone clarify what's
necessary with NFSv4 and what's doable?  i *should* be able to make it
to the meeting this eve, so i'd be ready to discuss this with anyone
who understands it well.

rday
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Robert P. J. Day                               Waterloo, Ontario, CANADA

            Linux Consulting, Training and Kernel Pedantry.

Web page:                                          http://crashcourse.ca
Twitter:                                       http://twitter.com/rpjday
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