On 10/26/2009 12:06 PM, Frank Ch. Eigler wrote:
Steve Dickson <SteveD(a)redhat.com> writes:
> [With the next nfs-utils rawhide build, I will be flipping the ]
> [switch that will cause all NFS client mounts to try NFS v4 first ]
> [...]
Is this really "first" or rather "only"? Was there a conclusion
about
whether the nfs client code would be changed to fall back from v4 to
v3 automatically?
It meant "first"... If the server does not support V4,
the mount will
automatically roll back to v3/tcp,v3/udp,v2/tcp,v2/udp...
The problem comes in when the server does support v4 but the exports are
not configured correctly (like pre F-12 Linux servers). In that case the
mount will fail with ENOENT which will look like:
mount.nfs: mounting laptop:/home failed, reason given by server:
No such file or directory
The there are a couple fixes to this problem:
1) Upgrade to an F-12 server
On a pre F-12 Server:
2) Added the '/ *(ro,fsid=0)' entry to the /etc/exportsfile and
reset the exports with 'exportfs -arv' (see exports(5) for details).
3) Set the 'RPCNFSDARGS="-N 4"' shell variable in the
/etc/sysconfig/nfs
file and restart the server via 'service nfs restart'
On a Rawhide Client:
4) Set the Defaultvers=3 in the /etc/nfsmount.conf file
5) Explicitly set the version (meaning don't do any server negotiation)
by either using the '-o v4' mount option on the command line or
set Nfsvers=3 in the /etc/nfsmount.conf file.
The first fixes two are preferred...
steved.