1. A method of grouping virtual machines, the method comprising: identifying, by a virtual server agent coordinator comprising computer hardware, a set of virtual machine provider systems in a primary storage system, each of the virtual machine provider systems including a virtual machine monitor and configured to host a set of virtual machines; accessing, by the virtual server agent coordinator, metadata for each of the virtual machine provider systems from the set of virtual machine provider systems; grouping, by the virtual server agent coordinator, the virtual machine provider systems into one or more groups based at least partially on the metadata for each of the virtual machine provider systems; assigning, by the virtual server agent coordinator, a set of virtual server agents to each group of virtual machine provider systems, wherein each virtual server agent is configured to back up data from at least one virtual machine in the primary storage system to a secondary storage system, wherein assignment of the set of virtual server agents among each group of virtual machine provider systems is based at least in part on a number of data streams available to each virtual server agent, and wherein a first virtual server agent associated with less data streams than a second virtual server agent is assigned to a first group of virtual machine provider systems that host smaller virtual machines than virtual machines hosted by a second group of virtual machine provider systems; and backing up the data from the at least one virtual machine in the primary storage system to the secondary storage system.