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Date:      Wed, 18 Nov 1998 13:47:22 -0800 (PST)
From:      Tom Bartol <bartol@salk.edu>
To:        Doug Rabson <dfr@nlsystems.com>
Cc:        freebsd-current@FreeBSD.ORG
Subject:   Re: NFS problems in -current
Message-ID:  <Pine.BSF.3.96.981118133307.429A-100000@eccles.salk.edu>
In-Reply-To: <Pine.BSF.4.01.9811180942150.21711-100000@herring.nlsystems.com>

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On Wed, 18 Nov 1998, Doug Rabson wrote:

> On Tue, 17 Nov 1998, Tom Bartol wrote:
> 
> > 
> > Hi all,
> > 
> > I've been seeing the following problem for a while now (since
> > 3.0-19981006-BETA) but was too busy at the time to report it or help
> > diagnose it further.  Now I've got some time on my hands...
> > 
> > I can fairly consistently wedge NFS writes to our server with the
> > following:
> > 
> > dd if=/dev/zero of=ick bs=8192 count=1000
> > 
> > which tries to write an 8MB file to our file server which is an Auspex.  I
> > have mounted Auspex from my 3.0-current machine (cvsupped and built this
> > morning) in NFSv3 mode.  This command will wedge one or more of the nfsiod
> > processes.  "ps -auwx | grep nfsiod" reports the following:
> > 
> > root     137  0.0  0.0   216   64  ??  I     9:12AM   0:02.31 nfsiod -n 4
> > root     138  0.0  0.0   216   64  ??  I     9:12AM   0:01.74 nfsiod -n 4
> > root     139  0.0  0.0   216   64  ??  D     9:12AM   0:00.27 nfsiod -n 4
> > root     140  0.0  0.0   216   64  ??  D     9:12AM   0:00.24 nfsiod -n 4
> > 
> > The two processes in state "D" are the wedged ones.  A separate machine
> > running -current from July 11 works fine.
> > 
> > Eventually all the nfsiod's get wedged and I'm forced to reboot.  NFS
> > reads work fine.
> > 
> > Is anyone else seeing similar behaviour?  What can I do to try to fine
> > tune a diagnosis and help solve the problem?
> > 
> > Thanks for your help,
> 
> The best place to start is to get a tcpdump of the set of transactions
> which wedged the iod.
> 

O.K.  I've got a tcpdump of nfs traffic during a successful dd of 800KB
and during a dd of 1600KB which resulted in a wedged nfsiod process.  I'm
not sure what to look for in the output.  I don't see any obvious problems
or major differences between the success and the failure, but then I'm not
an expert at reading tcpdump output.  Here is the command I used to
capture the data: 

tcpdump -s 192 -vv >& nfs_traffic

Which should see everything on my segment.  We have switched 100BT to the
desktop here and I have my own private port on the switch so my wire is
pretty quite (except for the occasional broadcast).  The traffic I
captured contains only a few non-nfs tidbits.  

So, should I post my output for some helpful expert to take a look at?
I'd sure like to see this problem fixed in -current...

Tom





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