Which setting on a virtual machine ensures it always gets the appropriate resources during host overload?

Setting CPU and Memory Reservations on a virtual machine ensures that it always receives the necessary resources, particularly during periods of host overload. When these reservations are in place, they guarantee a minimum allocation of CPU and memory resources to the virtual machine, irrespective of the overall demands on the host server.

In situations where multiple virtual machines are competing for limited resources, reservations make certain that the specified VM has access to the resources it requires to operate effectively. This is crucial for applications that have specific performance requirements and cannot afford to be starved of resources. By establishing these reservations, administrators create a safety net for critical workloads, ensuring they perform optimally even during peak loads or resource contention scenarios.

Other options, while beneficial for managing resources, do not provide the same level of guarantee as reservations. For example, High Availability Admission Control focuses on maintaining availability rather than ensuring resource allocation. High Performance Power Policy optimizes power usage rather than directly addressing resource allocation during overload. Lastly, setting CPU and Memory Shares to High can improve the allocation priority under contention, but it does not ensure minimum resource availability as reservations do.