[Beowulf] NFS Read Errors

Joshua Baker-LePain jlb17 at duke.edu
Wed Dec 5 12:26:20 EST 2007

On Wed, 5 Dec 2007 at 9:55am, Michael H. Frese wrote

> Clearly, this puts a premium on using tcp for nfs.  All our attempts to do 
> that failed.  Well, both of them, anyway.  In the first one, we unmounted the 
> offending disk, modified its fstab entry, and remounted it.  We were pretty 
> careful in the second one, where we added tcp to the fstab argument, 
> unmounted all the remote disks, restarted all the nfsd's, and did 'mount -a'. 
> We got an error message in both cases that didn't obviously refer to the tcp 
> argument, but the mount didn't happen.  As I write this, I see references to 
> tcp mount requests in the mountd man page, so maybe we need to do a bit more 
> here.
> The Wikipedia article on nfs says this:  "At the time of introduction of 
> Version 3, vendor support for TCP as a transport-layer protocol began 
> increasing. While several vendors had already added support for NFS Version 2 
> with TCP as a transport, Sun Microsystems added support for TCP as a 
> transport for NFS at the same time it added support for Version 3."
> I'd like to know what version of nfs this server supports, but the man page 
> on nfsd doesn't say.  The man page on rpc.mountd says that it supports nfs 
> version 2 and version 3, but that "If the NFS kernel module was compiled 
> without support for NFSv3, rpc.mountd must be invoked with the option 
> --no-nfs-version 3."  Yet the /proc/procnum/cmdline for the running 
> rpc.mountd doesn't show a --no-nfs-version argument.  Clearly, both the 
> kernel and the server need to support the use of tcp.

Looking back through this thread, I don't see any details on the NFS 
server, only the clients.  What are the hardware and OS version of the NFS 

Grepping through the kernel config for RH9 shows it definitely did not 
support NFS over TCP *as a server*.  If your server is newer, though, and 
does support a TCP nfsd, then you may have to look at other stuff 
(firewalls rules, TCP wrappers, etc) as to why the TCP mounts didn't work.

Joshua Baker-LePain
QB3 Shared Cluster Sysadmin
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