Is there a way to determine which resource (i.e. disk, cpu, memory) is the most constrained resource?
You can use the performance tab in the VI client to start to get an idea of which resource is heavily used.
Here's a guide for using esxtop with a console/ssh session. When you start esxtop you can press c, d and m to switch between the CPU, disk and memory views.
http://www.vmware.com/pdf/esx2_using_esxtop.pdf
There's also a number of performance tuning links here which include a number of presentations from VMWorld 2006.
I would place the small unnoc appliance to have a nice overview of your architecture, it's quite simple to set up.
You can check this here:
Hope it helps
