How it works

Setup in CAST AI Console


You have two levels of downscaling available at your disposal:

  • Node deletion policy - just gets rid of nodes which are empty and no longer running any capacity
    • i.e. when you have various jobs running, past their run, nodes become empty, waste will get removed
  • Evictor - actively bin packing your cluster state and moving pods around to keep better utilisation of the nodes, by removing the empty ones with Node deletion policy

Bin packing flow


bin packing problem

  1. CAST AI implemented Evictor component which solves bin-packing problem
  2. Evictor scans your cluster on minute basis
  3. It identifies pods running on the underutilised nodes & checks whether they could be scheduled somewhere else
  4. When such combination of nodes & pods are found, Evictor cordons the node -> drains it, and the workloads get moved elsewhere, achieving less wasteful packing of the cluster
  5. Once the nodes becomes empty, Node deletion policy which should be enabled, will end up removing the empty node