1. A virtualized distributed computing system comprising: a first host system that includes one or more processors, one or more memories, and a management-server agent, the first host system executing an original virtual machine and interconnected with the management server through a network; a second host system that includes one or more processors, one or more memories, and a management-server agent, the second host system interconnected with the first host system and the management server through the network; and the management server, which coordinates a live-virtual-machine migration operation that moves the original virtual machine to the second host system, during which the contents of one or more memory pages are transferred from physical memory within the first host system to a physical memory within the second host system through a remote-data memory access interface to a network-interface controller on one or both of the first and second host systems; wherein the original virtual machine is moved from the first host system to become a relocated virtual machine executing on the second host system with minimal interruption in execution, on the order of less than one to three seconds, by moving an execution image of the virtual machine from the first host system to the second host system, moving swap files of the virtual machine from the first host system to the second host system, moving shared-memory-page and non-shared-memory-page lists for the virtual machine from the first host system to the second host system, moving modified physical-memory pages to which guest physical pages of the virtual machine are mapped from the first host system to the second host system; terminating execution of the original virtual machine on the first host system, and resuming execution of the relocated virtual machine on the second host computer.