Garbage Collector

When your nodes are running for some time you might find a lot of terminated containers and container images unreferenced by any pods consuming your container storage. In Docker environment you would execute docker rm and docker rmi to get rid of this objects. In Openshift alternatively you could leverage built in Garbage Collector which can do this for you automatically in the background. 

Garbage Collector is enabled by default in Openshift however with no limits for number of terminated containers and very high limits for unreferenced images storage space. You can adjust this defaults by setting kubeletArguments section of the node-config.yaml: 

kubeletArguments:

  ...
  maximum-dead-containers-per-container:
  - '1'
  maximum-dead-containers:
  - '50'
  minimum-container-ttl-duration:
  - 10s
  image-gc-high-threshold:
  - '70'
  image-gc-low-threshold:
  - '60'

You could learn more about this useful functionality in Openshift docs.