A hypervisor-exchange process includes: suspending, by an “old” hypervisor, resident virtual machines; exchanging the old hypervisor for a new hypervisor, and resuming, by the new hypervisor, the resident virtual machines. The suspending can include “in-memory” suspension of the virtual machines until the virtual machines are resumed by the new hypervisor. Thus, there is no need to load the virtual machines from storage prior to the resuming. As a result, any interruption of the virtual machines is minimized. In some embodiments, the resident virtual machines are migrated onto one or more host virtual machines to reduce the number of virtual machines being suspended.