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<DIV><FONT face=Arial size=2>2.4.7 kernel performs horribly on the dual Xeon
platforms because it does not </FONT></DIV>
<DIV><FONT face=Arial size=2>support </FONT><FONT face=Arial size=2>IRQ
balancing and DMA transfer on the IDE bus. If you are using an</FONT></DIV>
<DIV><FONT face=Arial size=2>IDE disk on the nodes, disk performance is very
slow which might affect your</FONT></DIV>
<DIV><FONT face=Arial size=2>application.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Jeff</FONT></DIV>
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style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=G.de-With@herts.ac.uk
href="mailto:G.de-With@herts.ac.uk">G.de-With</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=beowulf@beowulf.org
href="mailto:beowulf@beowulf.org">beowulf@beowulf.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Thursday, September 26, 2002 7:16
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> BEOWULF cluster hangs</DIV>
<DIV><BR></DIV>Hello
<P>Since a month we have a LINUX BEOWULF cluster, the clusters contains 7
P4 dual processor 2GHz computers, with 8Gb of RAM per machine. For our
network we have used Gigabit ethernet.
<P>The problem we have with our cluster is as follows. <BR>When running large
computational fluid simulations the simulation starts to slow down. At some
point the response of the computer is so poor that we have to kill the
simulation. In a worst case when the simulation was running overnight the
computer hangs and a reset of the computer is necessary. <BR>Nevertheless,
even when we manage to kill the simulation in time the computer remains very
slow and a reboot is necessary to regain full computer power.
<P>My first suspicion was that the computer simply started swapping, but there
is no swap space being used, instead free RAM memory is still apparent
<BR>(between 5-10%) and only 90% of the RAM is in use whereby 50% is cached
and another 50% is in usage. In addition the cpu usage is very low as well.
<P>May be it is of use to mention that this problem occurs with both
sequential and parallel simulations. <BR>
<P>On our cluster we are running RH7.2 with the LINUX kernel version 2.4.7-10.
We have set-up our cluster using oscar-1.2.1rh72. The /home partition on the
world client is a shared via the network using NFS.
<P>/etcfstab
<P>192.168.1.100:/home /home nfs rw 0 2 <BR> <BR>
<P>1) In case anyone could do me some suggestions why our computers are
slowing down/hanging or if some one has got a similar experience please let me
know. <BR>2) To my understanding the most important indicators to indicate the
computer usage are: <BR>- memory usage <BR>- cpu usage <BR>Are there other key
components/indicators which could lead to a reduction in computer performance,
and if so how can I see the status of them.
<P>Govert <BR> <PRE>--
------------------------------------------------------------
| Dr. Govert de With Research Fellow |
| Fluid Mechanics Research Group |
| University of Hertfordshire |
| Tel: 01707 284124 Fax: 01707 285086 |
------------------------------------------------------------
| Der Horizont vieler Menschen ist ein Kreis mit Radius Null |
| und das nennen sie ihren Standpunkt. |
------------------------------------------------------------</PRE>
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