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List: beowulf
Subject: [Beowulf] NASTRAN on cluster
From: "Currit, Dennis" <Dennis_Currit () atk ! com>
Date: 2005-04-11 17:01:14
Message-ID: 7B8D37027B57D7459984035D83864E360682AF06 () exchangeut1 ! atk ! com
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We just installed a small cluster and are running NASTRAN 2005 on it. This is the \
first cluster we have set up, so we are beginners. Anyway, the cluster consists of 5 \
Dell Precision 470 workstations running Fedora Linux. Each has 4 GB RAM, 2 160 GB \
SATA drives and dual Xeon 2.8 ghz processors. It seems to run pretty well; there \
were no real tricks. Some of the NASTRAN bdf files needed to be modified a little in \
order to run, usually by removing statements that assigned specific file paths and \
names to scratch and dbs files. One thing to consider is that NASTRAN doesn't seem \
to make very good use of dual processor machines. For example, I have 5 dual \
processor machines. If I specify dmp=10 on the NASTRAN command, it starts 2 \
processes on each machine and runs MUCH slower than if I had it only started 1 \
process per machine. There is a (undocumented?) command (sys107=2) that specifies \
that each machine has two processors. It improves performance somewhat. On a test \
job, I got the following results:
Single Machine 523 minutes
5 node cluster (dmp=5) 148 minutes
5 node cluster (dmp=10) 199 minutes
5 node cluster (dmp=5 sys107=2) 128 minutes
Also, I didn't do any RAID. My thought was that I would rather put /tmp and /scratch \
on different physical drives. After I had it set up, I talked with MSC and they \
recommended using RAID 0. They also recommended using ext2 for /scratch rather than \
ext3. I changed that and my test job ran in 125 minutes.
Also, MSC NASTRAN uses a maximum of 2 GB or RAM under 32 Linux, but I have seen \
documentation that suggests you get a real perfomance benefit by having at least 3 GB \
on each node. Along this line, I couldn't get jobs to run when I specified mem=2gb, \
but they did run when I specified mem=500mw (500 mega words, just under 2 GB).
My impression is that performance is limited by CPU speed, not I/O. I would spend \
more money on faster (maybe 64 bit) processors than in optimizing the disk system.
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<P><FONT SIZE=2 FACE="Arial">We just installed a small cluster and are running \
NASTRAN 2005 on it. This is the first cluster we have set up, so we are \
beginners. Anyway, the cluster consists of 5 Dell Precision 470 workstations \
running Fedora Linux. Each has 4 GB RAM, 2 160 GB SATA drives and dual Xeon 2.8 \
ghz processors. It seems to run pretty well; there were no real tricks. \
Some of the NASTRAN bdf files needed to be modified a little in order to run, usually \
by removing statements that assigned specific file paths and names to scratch and dbs \
files. One thing to consider is that NASTRAN doesn't seem to make very good use \
of dual processor machines. For example, I have 5 dual processor \
machines. If I specify dmp=10 on the NASTRAN command, it starts 2 processes on \
each machine and runs MUCH slower than if I had it only started 1 process per \
machine. There is a (undocumented?) command (sys107=2) that specifies that each \
machine has two processors. It improves performance somewhat. On a test \
job, I got the following results:</FONT></P>
<P><FONT SIZE=2 FACE="Arial">Single Machine \
\
523 minutes</FONT>
<BR><FONT SIZE=2 FACE="Arial">5 node cluster (dmp=5) \
\
148 minutes</FONT>
<BR><FONT SIZE=2 FACE="Arial">5 node cluster (dmp=10) \
\
199 minutes</FONT>
<BR><FONT SIZE=2 FACE="Arial">5 node cluster (dmp=5 sys107=2) 128 minutes</FONT>
</P>
<P><FONT SIZE=2 FACE="Arial">Also, I didn't do any RAID. My thought was that I \
would rather put /tmp and /scratch on different physical drives. After I had it \
set up, I talked with MSC and they recommended using RAID 0. They also \
recommended using ext2 for /scratch rather than ext3. I changed that and my \
test job ran in 125 minutes. </FONT></P>
<P><FONT SIZE=2 FACE="Arial">Also, MSC NASTRAN uses a maximum of 2 GB or RAM under 32 \
Linux, but I have seen documentation that suggests you get a real perfomance benefit \
by having at least 3 GB on each node. Along this line, I couldn't get jobs to \
run when I specified mem=2gb, but they did run when I specified mem=500mw (500 mega \
words, just under 2 GB).</FONT></P>
<P><FONT SIZE=2 FACE="Arial">My impression is that performance is limited by CPU \
speed, not I/O. I would spend more money on faster (maybe 64 bit) processors \
than in optimizing the disk system. </FONT></P>
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