NFS timeout trying to copy large file

Kevin Wang rightsock at gmail.com
Wed Jan 5 00:38:27 UTC 2005


Check your mtu.  if there's a mismatch, that may account for the problem.

If there is a mtu mismatch, you shoudl also ahve problems with any
file over about 1k in size, but 2k should definitely show the same
problem.  Please test and report back.

try also ping's with large packet sizes (man ping for description of
the -s argument) that will create a packet over 1500 bytes and work
your way down until it work. that's the mtu that you need.

   - Kevin

On Tue, 4 Jan 2005 05:22:36 -0500 (EST), Robert P. J. Day
<rpjday at mindspring.com> wrote:
> On Mon, 3 Jan 2005, David Cary Hart wrote:
> 
> > On Mon, 2005-01-03 at 15:51 -0500, Robert P. J. Day wrote:
> > >   i have an embedded system on which i can bring up a PPP connection
> > > to a host running FC2T3 (yes, we'll upgrade to FC3 one of these days).
> > >
> > >   currently, after we start the PPP connection, we can NFS mount a
> > > directory from the host and copy a short file no problem ("short" =
> > > 184 bytes) from the host to the embedded system.
> > >
> > >   however, copying a sizable file (600K) over the same PPP/NFS
> > > combination fails -- the "cp" command sits there for several seconds,
> > > and eventually, we get an NFS timeout error.
> > >
> > >   here's the output from tcpdump on the ppp0 interface -- i'm not sure
> > > what to make of the latter part of the output.  thoughts?
> 
> > Which NFS version?
> 
> the FC2T3 system has the rpm nfs-utils-1.0.6-20.  and i managed to
> omit an important piece of info.  when we establish the NFS mount
> through the ethernet interface, the copies work just fine.
> 
> OTOH, when we do this across the PPP interface, that's where the large
> file copies just hang.  so it's looking like there's some kind of
> bottleneck with the PPP interface for NFS transfer.
> 
> > > 16:38:10.679007 IP 10.1.1.96.2590943354 > 10.1.1.97.nfs: 88 access [|nfs]
> > > 16:38:10.679169 IP 10.1.1.97.nfs > 10.1.1.96.2590943354: reply ok 120 access c 0000
> > > 16:38:10.759030 IP 10.1.1.96.2590943355 > 10.1.1.97.nfs: 100 getattr [|nfs]
> > > 16:38:10.759204 IP 10.1.1.97.nfs > 10.1.1.96.2590943355: reply ok 112 getattr REG 100644 ids 0/0 [|nfs]
> > > 16:38:10.837982 IP 10.1.1.96.2590943356 > 10.1.1.97.nfs: 88 access [|nfs]
> > > 16:38:10.838234 IP 10.1.1.97.nfs > 10.1.1.96.2590943356: reply ok 120 access c 0000
> > > 16:38:10.919969 IP 10.1.1.96.2590943357 > 10.1.1.97.nfs: 100 getattr [|nfs]
> > > 16:38:10.920227 IP 10.1.1.97.nfs > 10.1.1.96.2590943357: reply ok 112 getattr REG 100644 ids 0/0 [|nfs]
> > > 16:38:10.997223 IP 10.1.1.96.2590943358 > 10.1.1.97.nfs: 88 access [|nfs]
> > > 16:38:10.997416 IP 10.1.1.97.nfs > 10.1.1.96.2590943358: reply ok 120 access c 0000
> > > 16:38:11.078945 IP 10.1.1.96.2590943359 > 10.1.1.97.nfs: 100 getattr [|nfs]
> > > 16:38:11.079200 IP 10.1.1.97.nfs > 10.1.1.96.2590943359: reply ok 112 getattr REG 100644 ids 0/0 [|nfs]
> > > 16:38:11.158932 IP 10.1.1.96.2590943360 > 10.1.1.97.nfs: 104 access [|nfs]
> > > 16:38:11.159190 IP 10.1.1.97.nfs > 10.1.1.96.2590943360: reply ok 120 access c 0000
> > > 16:38:11.243980 IP 10.1.1.96.2590943361 > 10.1.1.97.nfs: 112 read [|nfs]
> > > 16:38:11.244317 IP 10.1.1.97.nfs > 10.1.1.96.2590943361: reply ok 520 read
> > > 16:38:11.244390 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:11.244408 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:11.443893 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:11.443920 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:11.643575 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:12.200775 IP 10.1.1.96.2590943361 > 10.1.1.97.nfs: 112 read [|nfs]
> > > 16:38:12.201133 IP 10.1.1.97.nfs > 10.1.1.96.2590943361: reply ok 520 read
> > > 16:38:12.201210 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:12.201229 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:12.400710 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:12.400738 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:12.600383 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:14.121482 IP 10.1.1.96.2590943361 > 10.1.1.97.nfs: 112 read [|nfs]
> > > 16:38:14.121750 IP 10.1.1.97.nfs > 10.1.1.96.2590943361: reply ok 520 read
> > > 16:38:14.121822 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:14.121840 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:14.321314 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:14.321342 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:14.520995 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:17.961900 IP 10.1.1.96.2590943361 > 10.1.1.97.nfs: 112 read [|nfs]
> > > 16:38:17.962172 IP 10.1.1.97.nfs > 10.1.1.96.2590943361: reply ok 520 read
> > > 16:38:17.962247 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:17.962265 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:18.161739 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:18.161766 IP 10.1.1.97 > 10.1.1.96: udp
> > > 16:38:18.361412 IP 10.1.1.97 > 10.1.1.96: udp
> 
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