Pods that use emptyDir volumes without storage quotas will fill up this storage, where the following error is present:
eviction manager: attempting to reclaim ephemeral-storage
Set a quota limits.ephemeral-storage, requests.ephemeral-storage to limit this, as otherwise any container can write any amount of storage to its node filesystem.
A sample resource quota definition
apiVersion: v1
kind: ResourceQuota
metadata:
name: compute-resources
spec:
hard:
pods: "4"
requests.cpu: "1"
requests.memory: 1Gi
requests.ephemeral-storage: 2Gi
limits.cpu: "2"
limits.memory: 2Gi
limits.ephemeral-storage: 4Gi
Another reason for this issue can be log files eating disk space. Check this question