Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!samsung!uunet!bcstec!iftccu!bressler
From: bressler@iftccu.ca.boeing.com (Rick Bressler)
Newsgroups: comp.sys.sequent
Subject: Re: network clusters
Message-ID: <1710003@iftccu.ca.boeing.com>
Date: 22 Feb 91 00:58:30 GMT
References: <27BD8836.5548@orion.oac.uci.edu>
Organization: Boeing Commercial Airplane Group
Lines: 63

>/ iftccu:comp.sys.sequent / iglesias@orion.oac.uci.edu (Mike Iglesias) / 11:29 am  Feb 16, 1991 /
>Can someone tell me what the "requests for clusters denied" means in
>netstat -m output?  We've been having some strange network problems
>with our Sequent Symmetry running Dynix 3.0.12, and it seems to be
>related to that, in that the problems occur when that number has
>increased.  I've included a copy of the netstat -m output at the end
>of this message. 
>
>
>Thanks,
>
>Mike Iglesias
>University of California, Irvine
>Internet:    iglesias@orion.oac.uci.edu
>BITNET:      iglesias@uci
>uucp:        ...!ucbvax!ucivax!iglesias
>
>
>
>499/2272 mbufs in use:
>	73 mbufs allocated to data
>	33 mbufs allocated to packet headers
>	162 mbufs allocated to socket structures
>	84 mbufs allocated to socket peers
>	123 mbufs allocated to protocol control blocks
>	3 mbufs allocated to routing table entries
>	19 mbufs allocated to zombie process information
>	2 mbufs allocated to interface addresses
>29/200 mapped pages in use
>584 Kbytes allocated to network (18% in use)
>0 requests for memory denied
>4456 requests for clusters denied
>----------

Another post had a pretty good description of mbufs, but I have a couple of
things to add.  Mbufs are also used in regular old piping! (surprise :(.
This has the effect of making some commands like ls -l and so on not operate!
The netstat output above tells me that you took a hit in your networking at
some point.  I had a similar problem.  If it continues, it will eventually
crash your portmapper and the problem will disappear until you reboot.
If you have NFS running, but don't need it, you might try not starting the 
mountd daemon.  That solved a similar problem for me until the real 
problem was found.

I am on a large network (30000+ devices) and sometimes they don't all 
broadcast at the correct addresses.  This in usually doesn't mess us up
very badly, but there was this one HP that insisted on rebroadcasting
these packets MANY times quickly, which overloaded the networking 
capability of our machine.  This machine was finally found and shot 
through the ethernet board and our problem disappeared.  In this case,
increasing our mbufs probably wouldn't have solved the problem. 

This particular problem showed up only when we were running NFS.  

You appear to be running the default configuration for the number of mbufs,
but that is enough for us, running about 40-60 users.  You might want to 
contact sequent, I found them to be helpful in tracking this problem down.

Other things that I have found that can cause this problem are broadcasts
from things like routed and rusers and so on.  These all generate large 
quantities of responses and they are buffered in mbufs.  Good luck!
--------
Rick.


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