Cinder Scheduler Weights¶

AllocatedCapacityWeigher¶

Allocated Capacity Weigher weighs hosts by their allocated capacity.

The default behavior is to place new volume to the host allocated the least space. This weigher is intended to simulate the behavior of SimpleScheduler. If you prefer to place volumes to host allocated the most space, you can set the allocated_capacity_weight_multiplier option to a positive number and the weighing has the opposite effect of the default.

CapacityWeigher¶

Capacity Weigher weighs hosts by their virtual or actual free capacity.

For thin provisioning, weigh hosts by their virtual free capacity calculated by the total capacity multiplied by the max over subscription ratio and subtracting the provisioned capacity; Otherwise, weigh hosts by their actual free capacity, taking into account the reserved space.

The default is to spread volumes across all hosts evenly. If you prefer stacking, you can set the capacity_weight_multiplier option to a negative number and the weighing has the opposite effect of the default.

ChanceWeigher¶

Chance Weigher assigns random weights to hosts.

Used to spread volumes randomly across a list of equally suitable hosts.

GoodnessWeigher¶

Goodness Weigher. Assign weights based on a host’s goodness function.

Goodness rating is the following:

  0 -- host is a poor choice
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 50 -- host is a good choice
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100 -- host is a perfect choice

VolumeNumberWeigher¶

Weigher that weighs hosts by volume number in backends.

The default is to spread volumes across all hosts evenly. If you prefer stacking, you can set the volume_number_multiplier option to a positive number and the weighing has the opposite effect of the default.