Check used space in Google Persistent Disk

I'll recommend running the following commands to view the pods/nodes current state:

• kubectl describe pod 'failing pod'
• kubectl get pod -o go-template='{{range.status.containerStatuses}}{{"Container Name: "}}{{.name}}{{"\r\nLastState: "}}{{.lastState}}{{end}}' 'failing pod'
• kubectl describe node 'node where pod is failing'
• kubectl get events

These commands can provide detailed information on the pods that might be failing, as well as the nodes where the pods are being created. This Kubernetes link has more information on how to determine the root cause for a pod failure.

For monitoring the resources used by pods, it's better to use the monitoring tools that Kubernetes suggest or the Web UI (Dashboard), as these tools can provide detailed information on the resources being used by every pod.

You can't see it in the disk preview as Faizan said, But you could Use Google StackDriver Monitoring tool to get a nice preview of your instances status.