What is the default admission control policy in a vSphere cluster that automatically recalculates as resources change?

The default admission control policy in a vSphere cluster that automatically recalculates as resources change is the Cluster Resource Percentage. This policy functions by allowing the cluster to maintain a specified percentage of cluster resources available for virtual machines, dynamically adjusting as resources are utilized or released. It ensures that if a host fails, there will still be enough resources available for the remaining virtual machines to function properly, considering the actual load and resource allocation at any given time.

As the resources within the cluster change—for instance, when virtual machines are powered on or off—this admission control policy re-evaluates the resource availability, which helps in maintaining the desired performance and availability of VMs without manual intervention.

This dynamic capability is crucial in environments where workloads can vary significantly, making it a reliable choice for ensuring continuous service availability while keeping resource allocation optimized. Other policies might offer static tolerances based on minimum requirements or reserved resources but do not adjust automatically based on real-time changes.