One advantage of using the multi-tenancy features in WebLogic Server is that you can get higher density. If you target multiple partitions to the same WLS cluster, then those partitions share the hardware and software stack, from the iron up through the Java virtual machine and the WLS infrastructure itself. This is great for efficient use of resources, but what about isolating those partitions from each other?
We've published a short article about the tension between density and isolation. It highlights how to set up partitions and virtual targets for either purpose. Please take a look!