Is it possible to span one huge VM across several physical commodity servers?

Solution 1:

There is a commercial product from ScaleMP called vSMP. It allows you to aggregate multiple x86 systems into a single virtual instance. I've never personally tried this before though, but I've been through a presentation from them. If I remember correctly, there are specific requirements for this to work, and you'll need to get some additional hardware (Infiniband for fast, low latency interconnects). It might cost a pretty penny too!

Solution 2:

There is no way to get the exact same functionality as a single 32-processor machine... with several separate servers. Your best bet is to look at clustering or grid computing. Done right, you can end up with comparable performance... and a higher level of high-availability. A lot of your question also depends on your "db" type. Microsoft SQL Server works significantly differently than MySQL or Oracle... and the scalability is also done completely differently.

Alternatively... you may want to consider letting someone do the database for you... like using the EC2 RDS...

Sadly, there is no way to combine several physical servers together & slap vmware on them and end up with a singular uber-powerful virtual server.