Alexey Solofnenko blog

Being a mathematician (and a little bit a physicist) I always felt something is wrong with hydrogen cars idea. Besides the promise of higher cruising range, each additional transformation reduces overall efficiency factor causing even more energy to be used per unit of work (or per mile). I would prefer that all that money would be used on development of better batteries, so cars could drive about 400 miles without recharging.

The idea of using VMWare to save energy is somewhat similar - reducing overall computer efficiency to be able to pack more services on less hardware. Lets review theoretical benefits of computer virtualization:

• automatic distribution of computer resources between VMs
• automatic starting and stopping VMs
• automatic VM relocation between computers
• services isolation

And the cost - less VM performance.

However, if you look closer at the benefits, you will notice they are similar to benefits of Java. Instead of virtualizing the whole OS, Java virtualizes just processes while generating code that executes close to native speeds (sometimes faster, sometimes slower, depending on what you are doing) and Java code has much better portability between computers with different architectures. I know it first hand - after we moved some parts of our build processes from slow Windows VMs to a single Solaris box, we saved hours!

So what is the conclusion - use Java to save energy and adding one more level of indirection is usually not the best solution.