1. A method for placing virtual machines in a collection, the method comprising: determining, by a computing device, a compatible set of hosts prior to placing virtual machines in the collection, wherein the compatible set is determined on the basis of the compatibility of types of resources in the host with virtual machines in the collection; determining, by the computing device, a plurality of equivalence sets of hosts from the compatible set of hosts prior to placing virtual machines in the collection, wherein hosts in an equivalence set of hosts are considered similar; selecting an equivalence set of hosts in the plurality of equivalence sets to place the virtual machines in the collection; and placing at least a portion of the virtual machines in the collection on one or more hosts in the selected equivalence set of hosts; wherein determining the plurality of equivalence sets of hosts comprises at least one of: using a symmetry property to determine the plurality of equivalence sets of hosts, wherein using the symmetry property comprises: evaluating whether a first host that has a virtual machine assumed to be placed on the first host is similar to a second host; and if the second host is similar, using the symmetry property to evaluate similarity of other hosts; and using a transitivity property to determine the plurality of equivalence sets of hosts, wherein using the transitivity property comprises: evaluating whether a first host that has a virtual machine assumed to be placed on the first host is similar to a second host and a third host; and if the second host and the third host are similar, using the transitivity property to evaluate similarity of other hosts.