F12 NFS Failures

[John Austin]

On Mon, 2009-11-23 at 15:00 -0800, Rick Stevens wrote:
> On 11/21/2009 10:41 AM, John Austin wrote:
> > On Sat, 2009-11-21 at 11:11 -0700, Greg Woods wrote:
> >> On Sat, 2009-11-21 at 10:09 +0000, John Austin wrote:
> >>
> >>>
> >>> When copying a large file (2.7GB) from the server to the
> >>> F12 m/c a complete freeze of the F12 machine occurs.
> >>
> >>
> >> I haven't seen freezes, but I have seen corruption when trying to copy
> >> large files (e.g. like a DVD iso image) via NFS. In fact, this happened
> >> to me when I was trying to install an F12 virtual machine on my F11 box
> >> (so I could try it out before deciding whether or not to bite the bullet
> >> and upgrade the host OS). I copied over the DVD iso image, then tried to
> >> install a VM from it, and it failed the media test. Sure enough, it also
> >> failed the sha256sum test. Copying the same DVD iso file via scp instead
> >> worked fine. I do not trust NFS for large files.
> >>
> >> --Greg
> >>
> >>
> >
> > Hi Greg
> >
> > That's interesting and very worrying - surely it can't/shouldn't happen!
> >
> > I have been using NFS for years for all types/sizes of files and
> > never had a problem until the last couple of months.
> >
> > 1.  The Centos/RHEL 5.3/5.4 kernel had a serious bug that has been fixed with the
> > 	latest kernel update
> >
> > 2.  Now this F12 problem
> >
> > Surely a very large worldwide community uses NFS ?
> >
> > OK the F12 case could be my finger trouble or even a hardware problem
> >
> > I will install F12 on a second machine and test again (against the same server)
> 
> Can you verify that you run into the same issue if you run NFS over TCP
> as opposed to NFS over UDP (it's an option in the mount command on the
> client, use either "proto=tcp" or "proto=udp").
> 
> By default, the system queries the server and selects a protocol based
> on what's being asked of it.  See the "TRANSPORT METHODS" section of
> "man nfs".
> ----------------------------------------------------------------------
> - Rick Stevens, Systems Engineer                      ricks at nerd.com -
> - AIM/Skype: therps2        ICQ: 22643734            Yahoo: origrps2 -
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Hi Rick

Many thanks for the reply - you have found a work-around !!

Just tested my machine with UDP and TCP
This was using md5sum for about 10GB over the NFS mount

1. The default for F12/Centos5.4 appears to be TCP - which freezes
2. Forcing UDP gives NO errors for 10GB transfer
3. Forcing TCP gives a freeze

Having briefly read the man pages this is the opposite of what I would
expect and of what you suggest !!

There must be a timing problem somewhere - 

Please see the other thread "Sky2 NIC Problem? - Was F12 NFS Failures"
for other tests I have carried out

Regards

John