oVirt and RHEV include cluster level policy options for ensuring an even distribution of virtual machines is maintained across a cluster. These policies are only engaged however when load on a single host reaches a given threshold which is generally quite high.

In some environments it may be desirable to keep these thresholds high while also maintaining a somewhat even spread of virtual machines across the hosts in each cluster.

The ovirt-force-balance script forces the balancing of virtual machines across an oVirt or RHEV environment. Currently this is done using relatively "dumb" logic. Available CPUs and RAM are not compared to virtual machine requirements, instead approximately equal hosts and virtual machine workloads are assumed. Balancing is formed by determining the number of hosts and virtual machines in the cluster. This is used to determine the optimum number of virtual machines per host as virtual machines divided by hosts.

The script then loops through the hosts in the environment and for each over utilized host initiates virtual machine migrations to bring the number of virtual machines on the host down to the optimum number.

Please note that this script has been developed and tested with the oVirt/RHEV 3.x series only.