Configuring JVM Parameters
Use
This procedure enables you to view and edit the Java Virtual Machine (JVM) parameters using the Config Tool. The JVM is used for running the AS Java and all deployed applications. You can change the values in the configuration template or in the configuration of a specific instance.
If you want your settings to be valid for all instances, select the template and choose the VM Parameters or VM Environment tab.
The template configuration is valid for those instances that do not have custom configuration.
If you want to set JVM parameters for a particular instance, you have to select the instance and choose the VM Environment or VM Parameters tab.
Prerequisites
The Config Tool is properly connected to a database.
More information:
Connecting to
a Database.
Procedure
Start the Config Tool by double clicking the configtool script file in <SAP_install_dir>/<system_name>/<instance_name>/j2ee/configtool directory.
Configuring JVM Environment Properties
...
1. Choose View → Expert Mode.
2. Choose the cluster template or the instance you want to configure.
3. Select VM Environment.
4. Select a property from the table list on the right.
5. In Default property data, you can see the default value of the property.
6. In Custom property data, you can enter a new custom value for the property.
Avoid editing properties which values are not static, such as DebugPort and ClassPath.
7. Choose Set.
8.
Choose 
Apply
Changes.
9. Restart the cluster.
Configuring JVM Parameters
...
1. Choose View → Expert Mode.
2. Select VM Parameters.
3. In VM Type, you can make configuration changes that are specific to the selected JVM. These changes apply only if the current platform and vendor matches the selected ones. GLOBAL changes apply to all vendors and platforms.
We recommend that you use SAP JVM on all supported platforms.
4. Select one of the following tabs and view the template properties contained therein:
○ Memory – JVM memory settings.
■ JVM heap size
■ If you want to increase the JVM heap size, we recommend that you change only the maxHeapSize directly by typing the needed memory value (in megabytes) in the Custom value field.
■ JVM perm size
■ If you want to adjust the JVM perm size, choose the appropriate JVM vendor.
■ Not all JVM vendors support perm size configuration.
If you enter an illegal value (for example, the value is not a number), the AS Java will not start. If you enter a value that is too low, the AS Java will experience problems and may restart.
○ System – All system properties usually specified with -Dxx=yy (for example, -DmyKey=myValue). If you want to add a custom property, choose New. The Config Tool automatically adds –D to all newly-entered parameters.
○ Additional – Any additional parameters, supported by the VM (for example, -verbose:gc). To add JVM parameters, choose New. The actual parameters used by a running JVM can be seen in the development trace file of the corresponding server process.
For example,
key="-agentlib:myagent"
value="port=12345,dir=C:/Mydir"
Results in parameter: "-agentlib:myagent=port=12345,dir=C:/Mydir".
By default, all properties are enabled.
5. If you want to disable a property, select it and choose Disable.
The property is added to Custom parameters.
You cannot delete default template properties. Using the Disable option you can only deactivate a certain property.
6. If you want to change the value of a specific property, select it and in Custom value, enter the new value.
7. Choose Set.
8.
Choose Apply
Changes.
9. Restart the cluster.
More Information
The table below shows memory settings. The following are calculated by the configuration templates:
● PermSize (MB)
● MaxPermSize (MB)
● Server processes
● MaxHeap/Server Process
These values are calculated by production mode formulas.
In this case, PermSize values are equal to MaxPermSize values.
CPU Cores |
Memory (MB) |
PermSize (MB) |
MaxPermSize (MB) |
Server processes |
MaxHeap/server process |
1 |
2048 |
450 |
450 |
1 |
697 |
2 |
2048 |
450 |
450 |
1 |
697 |
4 |
2048 |
450 |
450 |
1 |
697 |
1 |
4096 |
655 |
655 |
1 |
1638 |
2 |
4096 |
655 |
655 |
1 |
1638 |
4 |
4096 |
655 |
655 |
1 |
1638 |
8 |
4096 |
655 |
655 |
1 |
1638 |
16 |
4096 |
655 |
655 |
1 |
1638 |
1 |
8192 |
1024 |
1024 |
1 |
3563 |
2 |
8192 |
1024 |
1024 |
1 |
3563 |
4 |
8192 |
1024 |
1024 |
1 |
3563 |
8 |
8192 |
1024 |
1024 |
1 |
3563 |
16 |
8192 |
1024 |
1024 |
1 |
3563 |
1 |
16384 |
1024 |
1024 |
1 |
5120 |
2 |
16384 |
1024 |
1024 |
1 |
5120 |
4 |
16384 |
1024 |
1024 |
2 |
3563 |
8 |
16384 |
1024 |
1024 |
2 |
3563 |
16 |
16384 |
1024 |
1024 |
2 |
3563 |
1 |
32768 |
1024 |
1024 |
1 |
5120 |
2 |
32768 |
1024 |
1024 |
1 |
5120 |
4 |
32768 |
1024 |
1024 |
3 |
5093 |
8 |
32768 |
1024 |
1024 |
4 |
3563 |
16 |
32768 |
1024 |
1024 |
4 |
3563 |
32 |
32768 |
1024 |
1024 |
4 |
3563 |