The Filter Scheduler weighs hosts based on the config
option scheduler_weight_classes, this
defaults to
nova.scheduler.weights.all_weighers,
which selects the only weigher available -- the
RamWeigher. Hosts are then weighed and sorted with the
largest weight winning.
scheduler_weight_classes=nova.scheduler.weights.all_weighers ram_weight_multiplier=1.0
The default is to spread instances across all hosts
evenly. Set the ram_weight_multiplier
option to a negative number if you prefer stacking instead
of spreading.
