[Beowulf] NFS Read Errors

Michael H. Frese Michael.Frese at NumerEx.com
Wed Dec 5 09:57:23 PST 2007


Thanks for the info on the nfs server in RH9.  We are using that 
distro unmodified out of the box, so to speak, so that is clearly 
blocks any possibility for fixing the problem in software.  As for 
the hardware, it was described earlier as follows:

[Old hardware generally: AMD Athlon 32-bit single (MSI KT4V) and dual 
(Tyan...) chip motherboards both running Redhat 9 one with the 
2.4.20-8 kernels, though one is the smp version; NetGear GA311 NICs; 
and a NetGear GS108 8 port Copper 1 GB/s switch.  The single 
processor motherboards have 32-bit PCI slots so their network speeds 
are limited to 300 kbps as shown by netpipe.  All of the LEDs at the 
ends of the cables show 1000Mb connections.]

Thanks again for your help.


At 10:26 AM 12/5/2007, Joshua Baker-LePain wrote:
>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 server?
>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
>Beowulf mailing list, Beowulf at beowulf.org
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