Is there an efficient way to check the usage for PV/PVC in Kubernetes

Question

For example, I have 50 Gib PV/PVC and grant to one Pod, I just want to check usage of the storage

The way I am just following is to set up a busybox pod with mounting the same PVC, then exec into the busybox to run df -h to check the storage.

I just want to know if there is an efficient way to do the same thing.

Attract

Answer 1

Depending on how often you need to do this you might look at the df-pv plugin for kubectl https://github.com/yashbhutwala/kubectl-df-pv

It does exactly what you are asking across all the pvs in a namespace or cluster. Once you've got it installed, just run kubectl df-pv and you are set.

Bonhomie

Answer 2

Unfortunately we don't have this at the moment. What I often do is querying on Prometheus (because I have a Prom cluster there) for the metrics kubelet_volume_stats_used_bytes for the information.

Or in the harder way, you can write an operator to watch a CRD which wraps the PVC and to display the usage of the PVC.

Tatouay

Answer 3

There are many types of PV-s (e.g. various cloud storage). Each of them might have a different way of getting this information. You could always use kubectl describe pv <pv-name> or kubectl get pv <pv-name> -o yaml. This might give you some information about the current state of the PV, but it might lack the information you need.

I assume though that you are using Local PV-s. In this case your solution to run df -h inside a container is not bad. One other thing you could do is to run this command on the node which hosts the PV directly.

Prognathous

thanks for your reply, actually the describe donot have usage storage. and I didnt use the Local PV, I am using the azure stroage. due to busybox is linux base, so the df -h could check the mount folder in busybox as my knowledge – Attract

You could also monitor your storage account in Azure: azure.microsoft.com/en-us/documentation/articles/…. – Personalty

yes, your correct. but as to company i am working on, the PaaS on azure are not visibility to devops, so I am just seeking a way in k8s. – Attract

Answer 4

You can try the below set of commands, I checked on AKS and found out it to be working fine.

kubectl get pods -n namespace1

Pick the pod_name currently using or mapped to the PV/PVC (Persistent Volume Claims) and since I used the mount directory on the PV hence I have used /mount to check its details & replace {pod_name} with actual pod_name.

kubectl exec -it {pod_name} -n namespace1 bash

df -h

ls -l /mount

Gruelling