System setup for the z/VM virtualization tests

Normally, you cannot define more than 768 MB of JVM heap on a 31-bit distribution of WebSphere Application Server. However, with SUSE, you can use the mapped_base support to enable your system to have up to 1 GB of heap. Note that unpredictable results occur if you go over the 1 GB mark. To enable this capability, you need to place the following line into the startServer.sh startup script:

echo 268435456 >/proc/self/mapped_base

The startServer.sh script now looks like the following (note that bold is added for emphasis only):

lnwas3:/opt/IBM/WebSphere/AppServer/profiles/default/bin # cat startServer.sh
#!/bin/sh
echo 268435456 >/proc/self/mapped_base
WAS_USER_SCRIPT=/opt/IBM/WebSphere/AppServer/profiles/default/bin/setupCmdLine.sh
export WAS_USER_SCRIPT
/opt/IBM/WebSphere/AppServer/bin/startServer.sh "$@"

We used a self-signed certificate for the authentication. For creating a self-signed certificate we used the gsk7ikm. The 31-bit JRE was needed so the Java™ environment variable and path to the 31-bit Java could be set by using the following:

• export JAVA_HOME=/opt/IBMJava2-s390-142/jre/
• export PATH=/opt/IBMJava2-s390-142/jre/bin:$PATH

To make the above settings persistent over reboots, the above commands need to be added to the /etc/profile.

Set the Java environrment variable and path by doing the following:

• export JAVA_HOME=/opt/IBMJava2-s390-142/jre/
• export PATH=/opt/IBMJava2-s390-142/jre/bin:$PATH

Using the gsk7ikm utility we:

• Created a key database
• Created a self-signed certificate (using lnweb1:lnweb1 as the name)
• Placed the certificate under the /opt/IBMIHS/security directory (we had to create this directory)

Add the following to the IHS configuration file /opt/IBMIHS/conf/httpd.conf:

Listen 443
<IfDefine SSL>
LoadModule ibm_ssl_module modules/mod_ibm_ssl.so
</IfDefine>
<IfDefine SSL>
     <VirtualHost 0.0.0.0:443>
     DocumentRoot /opt/IBMIHS/htdocs/en_US
     SSLEnable
     SSLClientAuth none
     SSLServerCert lnweb1:lnweb1
     Keyfile /opt/IBMIHS/security/key.kdb	
     </VirtualHost>
</IfDefine>

Using the configuration file, we made changes to the default WebSphere Studio Workload Simulator script that was provided with the Trade distribution. The changes we made were:

• The number of simulated clients, which are executed by worker threads, was varied. Runs were made with 3, 4, 5, and 6 simulated clients. These clients were varied in order to reach optimal throughput and, at the same time, keep the overall processor utilization at around 90%. We found that four simulated clients achieved this.
• The time limit (length of our runs) was set to 20 minutes.
• The "element delay" (or "think time") was kept at 0.
• The "xml_interval" is the interval in minutes when WebSphere Studio Workload Simulator will take a snapshot of its output. This output can be customized. We paid attention to pages per second, transactions per second, and response time. Our xml_interval was set to five minutes.

Along with the configuration file changes we made, we also made changes to the WebSphere Studio Workload Simulator script file itself. The changes we made were:

• Hostnames lnweb[1 thru 5] were added to each of the five sample scripts.
• For SSL, every occurrence of getpage and postpage were changed to getpage_ssl and postpage_ssl respectively.