Technologies are described herein for optimizing resource utilization in a collection of devices having hierarchical network layers. Some example technologies may identify packets exchanged between processes executed on collections of server computers. The hierarchical network layers may couple the collections of server computers. The technologies may determine virtual machine groups based on the identified packets. Each of the virtual machine groups may identify one or more virtual machines configured on the collections of server computers to execute one or more processes. The virtual machine groups may be configured to increase data traffic in a lower layer in the hierarchical network layers and to decrease the data traffic in a higher layer in the hierarchical network layers. The technologies may relocate the virtual machines between the collections of server computers according to the virtual machine groups.