Recently I received the same questions from multiple customers, if HA restarts a virtual machine will it be placed in the resource pool it belongs or will it be restarted in the root resource pool (cluster-level)?
The answer is that HA will restart the virtual machine in the root resource pool, DRS will move the virtual machine into the correct resource pool once DRS is invoked. As the default invocation period of DRS is 5 minutes, the virtual machine is active at the cluster level for no more than 5 minutes.
What about share values? What if the virtual machine has an large number of shares assigned to it, or maybe worse a low number of shares? During this 5-minute period the relative share value of the virtual machine might dominate the other child objects such as resource pools or its performance might be squeezed by the share values of the other child objects.
To address this situation, HA will “flatten” the share value of the virtual machine before power-on. This flatten process ensures that the virtual machine will get the resources it would have received if it was placed into the correct resource pool. After DRS re-parents the virtual machine and places it in the correct resource pool, the virtual machine will receive the original configured shares again.
