Does anyone know what the maximum heap size I can specify for a JVM under Windows 2000 Advanced Server. I have quad Xeon machine with 4 GB of RAM, if this helps. I've searched and I can't find any set limitations.

TIA,
Jamie

which jvm version vendor and version?

I'm using Sun JDK 1.3.1_01.

JDK 1.3.1 has a max heap size of 4GB in theory (a 32-bit address space) but can only address about 3Gb in practice.

-Xmx3072m should work. Even -Xms3072m should work on a machine with that much memory.

You can also use the mostly-undocumented -XX:+AggressiveHeap flag which maxes the heap size and does a bunch of of other mysterious things too. Fun. :)

Ethan

I think u just use the jdk1.3,and out of momery throws when running,
u can find it in sun bug list,u can expand the heap size to 128 or more
options is
-XX:MaxPermSize=128M

Currently, we are setting -Xmx 1024m with success. However, any multiple over this results in a failure to start the JVM.

ok,I just set the parameter like this
-Xms128m -Xmx512m -XX:MaxPermSize=128M
and choose jdk1.3.1_06 with it,the server is ok for a long time

We are using -Xmx to set this, but values over 1024m seems to work. Any other ideas?

Hi, I have not gone through complete Forums to understand if this issue is resolved, But i had faced same problem in setting the JVM Size for Tomact_Opts with more then 1 GB Memory. Then i realised that JVM's are different for the different types of the Processors that we use for Windows. Based on your Windows OS processor if you could download specific JVM and configure your Windows system properties to use them, Then i think this problem will get resolved. Infact i had this problem as my Windows server is based on AMD processor, so i downloaded AMD based JVM and now this server is running with 2 GB settings And also JAVA_OPTS settings to increase more then 1 GB of heap can be done only with 64 Bit OS. Kindly let me know if this helps. Thanks, Sreedhar