SUMMARY: FDDI/NFS Solaris 2.4

From: Phil Poole (poole@ncifcrf.gov)
Date: Mon May 20 1996 - 09:26:23 CDT


Howdy all,

        sorry it's been so long before summarizing this but I wanted to
        thoroughly test it.

        The original question:
        
        I am currently using SunLink 3.01 on a Dual attached Sparc 20
        running Solaris 2.4 and I have found that when using the
        FDDI interface for NFS traffic I get a multitude of errors.
 
        Especially a large number of retrys and timeouts. NFS erros
        abound. RPC: Unable to send, RPC: Unable to receive write
        error
 
        I was having a similar problem before when mounting to SunOS
        machines and found that changing the mtu on the FDDI interface to 1500
        (same as the ethernet) vs the 4352 (FDDI normal mtu) I was able to
        overcome the problem.
 
        Now I am attempting to mount disk from SGI's running FDDI and
        have been encountering the errors.
 
        It looks like Sun's have problems using FDDI for NFS.
 
        Has anyone had similar experiences or suggest a fix ?

Special thanks go to the following:

Casper Dik casper@holland.Sun.COM
Greg Kranz greg.kranz@amp.com
Alex Finkel afinkel@sunrah.pfn.com
Srinivasa R. Yalavarthy srini@concorde.com
Kevin Sheehan Kevin.Sheehan@uniq.com.au

Grahm, I hope this answers your questions too.
Grahm Markes markes@sunscreen.dtw.etn.com

As Casper and Srinivasa both suggested turning off mtu discovery fixed
the problem and allowed the Solaris machine to communicate with an mtu
of 4352 over the FDDI interface.

The command to do this manually is as follows:

/usr/sbin/ndd -set /dev/ip ip_path_mtu_discovery 0

And as Casper suggested I created the following /etc/rc2.d script:

--begin enclosed file ---

#!/bin/sh
# Added 4/23/96 by Phil Poole to avoid
# FDDI/NFS problems remove if causing problems
 
/usr/sbin/ndd -set /dev/ip ip_path_mtu_discovery 0
echo "Fixing MTU FDDI/NFS problems. "
echo " /etc/rc2.d/S999mtu_fix "

---end enclosed file

So far the problem has been absent and all the other Unix boxes in
house, SunOS, Solaris, and Irix have been happily talking to one another.

Fedor,
Fedor Gnuchev qwe@ht.eimb.rssi.ru

        It is true that SunOS machines have trouble with large file
systems but they shouldn't have any trouble with large packets, per
se.

        The routers that the NFS traffic must go through here should
be smart enough to resize the packets and break them down.

        Also, I first noticed the problem on another Solaris machine
that was only connected to the network via Ethernet..and on the same
subnet as my NFS server with FDDI. Even when I explicitly tried
mounting through the NFS servers ethernet interface the time-outs
occurred. Apparently eventhough my NFS request was going into the
server via the ehternet..the responce was returning through the FDDI.

Oh well..hope this helps the current person posing NFS/FDDI questions.

Later all. thanks again.

-- 
       Phil Poole	| SUN Unix Administrator
     poole@ncifcrf.gov	| Frederick Biomedical SuperComputing Center
      (301) 846-5721	| Frederick MD, 21702



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