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From: lwk@CAEN.ENGIN.UMICH.EDU.UUCP
Newsgroups: mod.computers.apollo
Subject: slow disks
Message-ID: <8703131556.AA00136@caen.engin.umich.edu>
Date: Fri, 13-Mar-87 05:56:43 EST
Article-I.D.: caen.8703131556.AA00136
Posted: Fri Mar 13 05:56:43 1987
Date-Received: Thu, 26-Mar-87 07:44:50 EST
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We have discovered a curious phenomenon. A large Fortran job which is
run on two dn3000, one disked, the other diskless and booted off the 
former, seems to run faster on the diskless node. Here are the facts 
in the case:
1. Both are dn3000s with 4 Megs. The disk is an MSD-154.
2. The nodes are part of a large network
3. The data and object files reside on a second disk elswhere in the
   network. The job is theoretically cpu bound, however. 
4. The dspst shell command shows the disked node version uses 20% of 
   the CPU time. It also shows heavey winchester I/O which I assume
   is paging. The diskless version uses 95% of the CPU time.
5. The program is 6Mb, and is mostly large double precision arrays
6. When the program was run simultaneously on both nodes, the diskless
   version used ~20% of the CPU time and the disked version ran ~10%.
7. netsvc -p xxx executed during run (6) above didn't seem to effect 
   anything.
Why would a diskless node run faster than disked node when both are using
the same disk? This question is important and may effect future purchases.
Can anybody out there (Apollo?) tell me whats going on??
 Woody Kellum <lwk@caen.engin.umich.edu>