Weird NFS problem

[Stuart Bailey]

I'm having trouble with NFS on a Fedora 3 server. The client machines are a 
mixture of HP Unix and Solaris (also samba is used for Windows clients).
Most of the time the NFS export point runs perfectly fine, a client have it 
mounted all the time, and files and directories can be listed as expected.
All users have write access.

However, occasionally (about once a day) the files in various directories 
disappear from the client machines. If I go to the server and cd to the 
troublesome directories, they immediately become available to the clients 
again. As a quick fix, I have created a cron job that runs ls -R for the root 
directory of the nfs export.

The only error I get in the logs is:
Jun 13 07:39:58 kelvin rpc.statd[2248]: Received erroneous SM_UNMON request 
from kelvin.test for 172.16.44.23
but this indicates a write access problem with /var/lib/nfs/statd/sm and sm.d. 
But I have checked that the rpc users has r/w access to these.

I tried a tcpdump and got the following:

13:27:36.751186 IP (tos 0x0, ttl  64, id 52539, offset 0, flags [DF], proto 6, 
length: 148) tescat2.680050 > kelvin.test.nfs:108 lookup [|nfs]
13:27:36.751223 IP (tos 0x0, ttl  64, id 14271, offset 0, flags [DF], proto 6, 
length: 160) kelvin.test.nfs > tescat2.680050:reply ok 120 lookup ERROR: No 
such file or directory post dattr:
13:27:36.751646 IP (tos 0x0, ttl  64, id 52540, offset 0, flags [DF], proto 6, 
length: 132) tescat2.680051 > kelvin.test.nfs:92 getattr [|nfs]


Based on this I have tried turning off client side attribute caching, to no 
effect.

I have exported the directories as such:

/data   172.16.44.0/24    (rw,async,insecure,insecure_locks,no_subtree_check)

I have also tried sync instead of async, and removing the no_subtree_check 
flag, also to no effect.
Other things I have tried:
        reducing the MTU on the network to 1000 from 1500
        

Any ideas would be appreciated.

Many thanks,

Stuart.
-- 
---------------------------------------
Stuart Bailey BSc (hons) CEng CITP MBCS
         LinuSoft (Proprietor)
           Linux Specialist
            (01953) 601294
            (07778) 383739
       http://www.linusoft.co.uk
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