Storage Capacity Tracking


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Storage capacity tracking allows the Kubernetes scheduler to make more informed choices about where to start pods which depend on unbound volumes with late binding (aka "wait for first consumer"). Without storage capacity tracking, a node is chosen without knowing whether those volumes can be made available for the node. Volume creation is attempted and if that fails, the pod has to be rescheduled, potentially landing on the same node again. With storage capacity tracking, the scheduler filters out nodes which do not have enough capacity.

For design information, see the enhancement proposal.


To support rescheduling of a pod, a CSI driver deployment must:

  • return the ResourceExhausted gRPC status code in CreateVolume if capacity is exhausted
  • use external-provisioner >= 1.6.0 because older releases did not properly support rescheduling after a ResourceExhausted error

To support storage capacity tracking, a CSI driver deployment must:

Further information can be found in the Kubernetes documentation.