I did not know about this, but someone pointed this out last week and I figured it was worth blogging about as this feature can potentially impact your design. (Think HA admission control policies and resource management)
When you create a VM in an Org vDC which is defined as a Reservation Pool you can actually manually set the shares per type of resource (memory and CPU) and also set a reservation and even a limit if and when needed. Pretty cool, but as you can imagine also very complex at some point to figure out to what it should be set.
Not necessarily that complex. For instance, many people are already used to giving their high priority VMs “high” shares. That can be done easily here as well.
Of course, even if you leave the shares as default, you are still getting the usual protection against noisy neighbors with the associated peace of mind.
Irfan