From: petav@Physik.TU-Muenchen.DE (Peter Averkamp)
Subject: Re: Slow writes to Ultrix 4.3 NFS server
Keywords: NFS server performance
Organization: Leibniz-Rechenzentrum, Muenchen (Germany)
Date: Fri, 20 Nov 1992 17:56:01 GMT

john@iastate.edu (John Hascall) writes:

>leb@Hypatia.gsfc.nasa.gov (Lee E. Brotzman) writes:
>}I manage an SGI 4D/340 running IRIX 4.0.1 and a DECstation 5000/125 running
>}Ultrix 4.3.  The user login directories of both machines are NFS mounted to 
>}each other.  I have found that when the DEC box writes files to the SGI, 
>}performance is good, however when the SGI tries to write to the DEC, throughput
>}is just awful.

>Is this in the FAQ?  If not it should be...

>Anyway, several vendors' NFS servers mis-implement the standard (on purpose).
>The NFS standard requires that writes be done "synchronously".  Some vendors
>allow you to set an option which makes NFS writes be done "asynchronously"
>which can gain you a massive performance increase -- but if your server has
>a catastrophic crash (and can't flush the disk buffers) you can have data
>integrity problems.  *** SGI ships their systems with ASYNCH as the DEFAULT ***
>If you run asynch-writes (and we have modified our DEC servers to do this) and
>you don't have them on a UPS you are running a massive risk.

>The "safe" option to make your Ultrix boxes faster is to buy PrestoServe
>for your NFS servers.

>John
>(if you have an Ultrix *source* license, I can provide the 1-line patch)
>-- 
>John Hascall                   ``An ill-chosen word is the fool's messenger.''
>Systems Software Engineer
>Project Vincent
>Iowa State University Computation Center  +  Ames, IA  50011  +  515/294-9551

There has been a long discussion about all this over and over some time
ago. Being tired of people talking about things many of them never have
tried out, i have put together an object-code patch for the versions
4.2 and 4.2a, so more people could try and take the risk and make their 
own experiences. I have mailed it to about 20 sites with a pledge to
inform me if >>anything<< >>ever<< goes wrong with a patched server. Up
to now, all i got were thanks from happy users. I know that 20 is very
bad statistics, so I'd like to see if there are even more dare-devils
out there taking this data-loss risk...
We don't have 4.3 yet, but you might try to use mine or figure out your
own patch. By the time we get 4.3, i'll update it; maybe some other
kind soul will do this before. I have binary patches for VAX/Ultrix(4.1)
also.

Now here's what you might want to do:

cd /sys/MIPS/BINARY
cp nfs_server.o nfs_server.o.orig
uuencode nfs_server.o.orig nfs_server.o|sed -e 's/P$ \!B0\!/P$ \!B0 /'|uudecode

the patched nfs_server.o's sums:
sum for 4.2  should be: 62555   104
sum for 4.2a should be: 15177   104
(The 'sum' of the uuencode-line is:18397  1, obtained by echo -n "stuff"|sum)
And finally, please mail:petav@e20.physik.tu-muenchen.de simply
saying that you've done it and if or what went wrong. I am really 
interested in getting better statistics to hear about anything that
ever went wrong, caused by the patch.

Please,Please be aware that using this will kick you completely off
limits; do not complain about anything to your dec service person if
you use a patched system. Do not blame or flame me! This is a
completely experimental modification that's only there to amuse those
who play with it. No Warranties, not even those for failure.

Many thanks to John Hascall who kicked off this whole issue and was so
kind to verify the patches against a source-patched object.


    Peter Averkamp


--
Peter Averkamp,                      | email:
Physics Department E20               | petav@radon.e20.physik.tu-muenchen.de
Techn. Univ. of Munich               | Phone: ++49 (89) 3209-2408
D-8046 Garching, Germany             | Fax:   ++49 (89) 3209-2338
Newsgroups: comp.unix.ultrix,comp.sys.dec