There are three resource controls that are available to determine how resources are provided to a virtual machine; these are shares, limits, and reservations. Limits, shares, and reservations can also be set on a resource pool and/or a vApp. A resource pool is a logical abstraction of resources from the root pool and is managed hierarchically using a parent-child relationship. Memory overcommitment happens when the physical memory installed on an ESXi host is less than the sum of memory allocated to all virtual machines as well as overhead. vSphere uses multiple memory reclamation techniques to prevent an ESXi host from crashing when physical memory is low. Transparent page sharing allows pages of memory that are identical to be stored in the same place. Ballooning requires VMware Tools to be installed. If necessary, the hypervisor can directly swap out guest physical memory to the swap file, which frees host physical memory for other virtual machines as well as the hypervisor.

With...