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.

Solution 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.

Solution 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.

Solution 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.

Solution 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

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Comments

[Vampire_D]

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

[Dávid Molnár]

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

[Vampire_D]

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.