WebSphere Application Server 31-bit versus 64-bit

The purpose of these test runs was to compare the 31-bit and 64-bit versions of WebSphere® Application Server.

Observations

Using the 64-bit version of WebSphere Application Server results in a slight degradation in transaction throughput but a significant increase in CPU utilization.

Conclusion

Switching a WebSphere Application Server 6.1 environment from 31-bit to 64-bit addressing uses additional CPU and storage resources because at least all addresses require twice the space. Therefore, using 64-bit mode can only be recommended if the application needs more than 31-bit addressing to accomplish its function. Further investigations are required to show what throughputs can be reached using a 64-bit WebSphere Application Server in an environment which requires 64-bit support.