Administering virtual machines in a distributed computing environment

A method of administering a plurality of virtual machines (‘VMs’) in a distributed computing environment, the distributed computing environment comprising a plurality of hosts, one or more of the hosts executing a virtual machine monitor (‘VMM’), each VMM supporting execution of one or more VMs, the method comprising:

• assigning, by a VMM manager, the VMMs of the distributed computing environment to a logical tree topology, including assigning one of the VMMs as a root VMM of the tree topology;
• and
• executing, amongst the VMMs of the tree topology, a gather operation, including:
• sending, by the root VMM, to other VMMs in the tree topology, a request to retrieve one or more VMs supported by the other VMMs;
• pausing, by the other VMMs, each VM requested to be retrieved;
• and
• providing, by the other VMMs to the root VMM, the VMs requested to be retrieved.