Verifying the Java heap size

The Java™ heap size determines the number of volume pairs that Copy Services Manager can manage.

Verifying the Java heap size for Copy Services Manager for Distributed Systems

The default Java heap size is 1280 MB, which supports fewer than 75,000 pairs. If you increase the Java heap size by 256 MB, support increases by 25,000 pairs.

When managing a Safeguarded Copy session, additional Java heap might be necessary. To help provide faster performance, the server caches the volume and backup in memory, and requires 0.8 KB per volume per backup. To determine the heap size that is necessary, take the number of H1 volumes in the Safeguarded Copy session, and multiply that by the number of backups that you need to keep, and then multiple that number by 0.8 KB.
Example: If a Safeguarded Copy session has 2000 volumes and you want to keep 250 backups, the calculation would be: 2000 * 250 * 0.8 KB = 400,000 KB = 400 MB

The Java heap should be set to a value that is below the calculation for non-Safeguarded Copy pairs, plus the calculation for Safeguarded Copy backups.

You can continue to increase the Java heap size until you reach the maximum heap size.

Recommended: If Copy Services Manager is running on the a DS8000 HMC, the default heap size is set to 1024 MB. If the memory calculation goes above 768 MB, it is highly recommended that Copy Services Manager runs on an external server instead of the HMC. Contact support if you have questions on where Copy Services Manager should run, and the heap size setting.

The install dir/liberty/wlp/usr/servers/csmServer/jvm.options file now holds the maximum heap size for distributed systems, and can be used to configure the session with the -Xmx parameter (for example, -Xmx1280m).

For more information about the maximum heap size, see the information about sizing the Java heap size in the IBM® SDK for Java Tools at https://www.ibm.com/developerworks/java/jdk/howdoi/index.html.

For more information about how to set up the Java heap size, see the WebSphere® Application Server V8.5 Liberty profile technote at http://www.ibm.com/support/docview.wss?uid=swg21596474.

Verifying the Java heap size for Copy Services Manager for z/OS Systems

The default Java heap size is 768 MB, which supports fewer than 50,000 pairs. If you increase the Java heap size by 256 MB, support increases by 25,000 pairs. You can continue to increase the Java heap size until you reach the maximum heap size.

When managing a Safeguarded Copy session, additional Java heap might be necessary. To help provide faster performance, the server caches the volume and backup in memory, and requires 0.8 KB per volume per backup. To determine the heap size that is necessary, take the number of H1 volumes in the Safeguarded Copy session, and multiply that by the number of backups that you need to keep, and then multiple that number by 0.8 KB.
Example: If a Safeguarded Copy session has 2000 volumes and you want to keep 250 backups, the calculation would be: 2000 * 250 * 0.8 KB = 400,000 KB = 400 MB

The Java heap should be set to a value that is below the calculation for non-Safeguarded Copy pairs, plus the calculation for Safeguarded Copy backups.

You can continue to increase the Java heap size until you reach the maximum heap size.

The path_prefix/opt/IBM/CSM/wlp/usr/server/csmServer/jvm.options file now holds the maximum heap size for z/OS, and can be used to configure the session with the -Xmx parameter (for example, -Xmx1280m).

For more information about the maximum heap size, see the information about sizing the Java heap size in the IBM SDK for Java Tools at https://www.ibm.com/developerworks/java/jdk/howdoi/index.html.

For more information about how to set up the Java heap size, see the WebSphere Application Server V8.5 Liberty profile technote at http://www.ibm.com/support/docview.wss?uid=swg21596474.