The OS disk is running out of space. 

Generally any linux filesystem gets critical at 95% full, but you may have problems at 85% full when running a Kubernetes cluster.

The optimal disk space may be different depending on how you've partitioned your disk.  In the default configuration, the kubernetes containers are on the same disk as the linux files (logs, etc).

You may place the logs or kubernetes containers on a different partition or a separate disk. 

• Disks with kubernetes containers fail at 85%.
• Other disks are critical at 95% full.

You may be able to solve the problem, or buy time, by deleting logs, deleting redgate clone containers or increasing size of the storage volume. 

Please make sure the correct partitioning when increasing the storage volume.