What happens when you select the "Reserve all guest memory (All locked)" check box when reserving memory for a VM?

When the "Reserve all guest memory (All locked)" check box is selected while configuring memory reservations for a virtual machine, it ensures that all the allocated memory for that VM is reserved in the physical host's memory. This means that the hypervisor will treat the total amount of memory specified for the VM as a locked resource, guaranteeing that it will always be available to the virtual machine regardless of any changes in memory demands or usage patterns.

This reservation effectively prevents the hypervisor from reclaiming memory from this VM for other VMs or processes, ensuring that the VM has guaranteed memory availability at all times. This is particularly useful in scenarios where stable performance is critical, as it mitigates the risk of memory contention and ensures that the VM can operate without the risk of being starved of resources.

By reserving all the guest memory, you create a predictable environment for the VM, allowing applications running within it to perform consistently without being affected by resource allocation changes that occur due to other VMs running on the same host.