NFS hangs Ultrix <=> Sequent

[Craig Woods]

Platforms:

Brand New DECstation 2100, ULTRIX WS v2.2D (ULTRIX 3.0?)

Sequent Symmetry, DYNIX 3.0.12, with NFS

We just added the DECstation to our network, and everything is fine (after a
lot of fun convincing the system to use a WREN V as the system disk!),
 EXCEPT: 
NFS access hangs reliably after a random (usually very small) number of writes
in either direction, from either machine. The hung processes go into Disk wait,
and never come out. No error messages, other nfs accesses work ok, they just
die.

Both systems get intermittent "NFS server not responding; NFS server ok"
messages, but even after the connection is restored, the processes remain hung.
I tried setting timeo=60 on the mounts, with no change.

Also, when the DECstation _unmounts_ the Symmetry's disks, it gets the error:
"Warning: umount: rpc authentification error;why = auth too weak(remote error)"
Mounting works fine.

We've tried turning portmon on and off on both machines, with no changes.

Both machines talk NFS reliably with the Sun on our network.

Has anyone else out there seen NFS problems like these? I'm totally baffled,
and I think it will take some time to straighten this out with Sequent support
(the timeo option was their first suggestion), since there are no error
messages to give them any clues. Until we fix this, the DECstation is a piece
of junk, with pretty good graphics.

Thanks in advance for any advice.

(In desperation, I'm going to upgrade to DYNIX 3.0.17 tomorrow (sigh, another
weekend down the tubes), since NFS appears to be slightly newer in this release
(it finally supports the "intr" option!))

Craig Woods		Software Leverage, Inc  	...!uunet!sli!craig
Systems Admin		Arlington, MA			craig%sli at uunet.uu.net