Kubernetes is a popular container orchestration platform used by many organizations to deploy and manage their applications. However, one of the common issues that Kubernetes users face is node disk pressure. When a node's disk is under pressure, it means that the node is running out of disk space. This can cause issues with application performance and availability. In this article, we will discuss how to troubleshoot Kubernetes node disk pressure and resolve the issue.
Identifying Node Disk Pressure
The first step in troubleshooting node disk pressure is to identify which node(s) are affected. You can use the following command to check the disk usage of all nodes in your Kubernetes cluster:
kubectl get nodes -o jsonpath='{range .items[*]}{.metadata.name}{" "}{.status.allocatable.storage}{" "}{.status.capacity.storage}{" "}{end}' | awk '{print $1,$2/$3*100"%"}
This command will output a list of all the nodes in your cluster along with their disk usage percentage. Nodes with high disk usage percentages are likely experiencing disk pressure.
Analyzing Pod Disk Usage
The next step is to analyze the disk usage of pods running on the affected node(s). You can use the following command to list all pods running on a specific node:
kubectl get pods --all-namespaces -o wide --field-selector spec.nodeName=<node-name>
Replace <node-name> with the name of the affected node. This command will output a list of all pods running on the specified node along with their namespace, name, and IP address.
Once you have identified the pods running on the affected node(s), you can use the following command to view the disk usage of each container within a pod:
kubectl exec <pod-name> -- df -h
Replace <pod-name> with the name of the pod. This command will output the disk usage of each container within the pod.
Resolving Node Disk Pressure
Now that you have identified which node(s) and pods are experiencing disk pressure, you can take steps to resolve the issue. Here are some tips to free up disk space on a Kubernetes node:
- Delete unnecessary pods: If there are pods running on the affected node(s) that are no longer needed, delete them using the following command:
kubectl delete pod <pod-name>
Replace <pod-name> with the name of the pod.
- Delete unused images: Docker images can take up a significant amount of disk space. Use the following command to list all images on the affected node(s):
docker images
You can then delete unused images using the following command:
docker rmi <image-id>
Replace <image-id> with the ID of the image you want to delete.
- Increase node disk size: If the above steps do not free up enough disk space, you may need to increase the size of the node's disk. This will require adding additional storage to the node.
Node disk pressure is a common issue that Kubernetes users face. By following the steps outlined in this article, you can identify which node(s) and pods are experiencing disk pressure and take steps to resolve the issue. Remember to regularly monitor disk usage on your Kubernetes nodes to prevent disk pressure from occurring in the future.
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