Heap Size How-To? Don't understand Note 723909

[Former Member]

Dear all,

I don't fully understand Note 723909

In my example I have a portal running on 7.0 SPS 12, Windows Server 2003 X64, Java j2sdk1.4.2_15-x64, with one CPU and 12 GB RAM.

My current settings are:

Java Home: C:/j2sdk1.4.2_15-x64

Max Heap Size (in MB): 2048

Java Parameters: -Djava.security.policy=./java.policy

-Djava.security.egd=file:/dev/urandom

-Dorg.omg.CORBA.ORBClass=com.sap.engine.system.ORBProxy

-Dorg.omg.CORBA.ORBSingletonClass=com.sap.engine.system.ORBSingletonProxy

-Djavax.rmi.CORBA.PortableRemoteObjectClass=com.sap.engine.system.PortableRemoteObjectProxy

-Dorg.xml.sax.driver=com.sap.engine.lib.xml.parser.SAXParser

-verbose:gc

-Xmx2048m

-Xms2048m

-Djco.jarm=1

-XX:PermSize=512m

-XX:MaxPermSize=512m

-XX:NewSize=320m

-XX:MaxNewSize=320m

-XX:SurvivorRatio=2

-XX:TargetSurvivorRatio=90

-XX:+PrintGCTimeStamps

-XX:+PrintGCDetails

-XX:+UseTLAB

-XX:SoftRefLRUPolicyMSPerMB=1

-Dsun.io.useCanonCaches=false

-Djava.awt.headless=true

-Xss2m

-XX:+UseParNewGC

-Djavax.security.auth.useSubjectCredsOnly=false

-Djava.security.krb5.conf=D:\usr\sap\EP2\SYS\global\kerberos\ID21169\krb5.conf

-Dsun.security.krb5.debug=true

Classpath: ./bin/boot/boot.jar;./bin/boot/jaas.jar;./bin/system/bytecode.jar;.

Parameters: <empty>

Are these settings ok? How can I calculate the correct Heap Size?

Are Max Heap Size (Dropdown box) and the parameter -Xmx2048m identical? do they have to be identical?

Thank you for your hints!!

Philipp

[i803734]

Hey Philipp,

Your setting seems to be fine.

On 64bit, the SAP recommendation is 2048 heap.

SAP prefers that you have smaller heap and more dialog instances or server nodes if you add them in the same host. You have plenty of RAM to do that but the fact that you have only 1 CPU some kind of nulls out the memory advantage you have. If you have a Dual Core or Quad Core it gives you the option to add one to two more server nodes on the same box. Go progressively as you do not to overload the box and get poor performance because of more IO & CPU load.

-Xms needs to be set.

-Xmx not always required but better as it reserves the RAM heap completely in one shot instead of progressively.

Regards,

Marc.