In the example, we have two nodes and 6 instances, all using external
storage. There are four small instances on one node, and two big
instances, requiring twice the amount of resources of a small instance,
on the other node. So, with respect to static data, the cluster
is already perfectly balanced. Using the default assumption of
dynamic usage, however, the cluster can be improved by moving
one small instance to the other node. The reason is, that by default,
all instances are assumed to use the same resources, and this measure
dominates, as all static resources are greatly underutilized.

Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Michele Tartara <mtartara@google.com>