1. In a distributed computing environment, a method of defragmenting a cluster service to service additional capacity requests on the cluster service, the method comprising: ranking servers in a cluster by free capacity and selecting a first server with the most free capacity; identifying one or more replicas from the selected first server to move to another server; determining the another server to which the one or more replicas from the first server can be moved by ranking other servers by available capacity and determining to move at least one replica of the one or more replicas to a server with a least actual capacity that could fit the one or more identified replicas; and moving the one or more replicas to the server with the least actual capacity that could fit the one or more identified replicas.