vCloud Allocation Models, vCenter Resource Pools, and Per VM Resource Settings, Say What?

Moving vApps Between Allocation Models

You can in fact move any given vApp while powered off to another vDC with a different allocation model.  There is a number of use cases where this could be useful.  The most common I can see is that you thought your vApp would be fine with Pay As You Go, but over time the vApp becomes more Tier 1 being utilized more and you simply want fixed payments.  You simply shutdown your vApp and move it to another vDC with the new allocation model.  By default you’re vApp will inherit the settings of that vApp.  However what I have found in limited testing is that certain moves require some manual intervention.  If you move INTO a Reservation Pool, any PER Virtual Machine settings that were previously on the vApp will remain.  I suspect this is because specifically with a Reservation pool the user can control the settings.  This means if you want to level the settings back to “Unlimited” with no reservations you need to change it manually before powering on the VM.  However moving from PAYG to AP, or out of RP to PAYG or AP the settings seem to adjust automatically.  This is most likely because those are system controlled no user controlled like the Reservation Pool model.

Summary

So taking all this into account the reason for all the information is to show at the end of the day all these settings can affect your cluster within vSphere.  Certainly read Duncan’s new HA/DRS book, and think about where you might see some interesting things happen in the environment,  like a VM not powering on due to HA Admission Control based on the placement and the usage of the resource limits and reservations.  For those that have never used vSphere pools in the past and are looking to VMware vCloud DIrector, hold on tight becuase you will start seeing a lot of these things get created.