The sds-local-volume module: FAQ

When to use LVM and when to use LVM-thin?

Use LVM (Thick) if you need maximum performance comparable to the drive’s performance. LVM (Thick) is easier to configure.

Use LVM-thin if you need to use overprovisioning. LVM-thin performance is lower than LVM.

Why can’t I create a PVC on the selected node?

Check that the csi-node pod is running on the selected node:

d8 k -n d8-sds-local-volume get po -owide

If the pod is missing, ensure that the node has all the labels specified in the nodeSelector field in the module settings. For more details, see Why are the sds-local-volume component service pods not created on the desired node?.

Why did the csi-node pod remain on the node after removing labels?

The node likely has LVMVolumeGroup resources that are used in LocalStorageClass resources.

Delete the dependent resources manually to avoid losing control over the created volumes. For instructions on checking dependent resources, see the Checking dependent LVMVolumeGroup resources on a node section.

Why are the sds-local-volume component service pods not created on the desired node?

The issue is likely related to node labels. The module uses nodes that have the labels specified in the nodeSelector field in the module settings.

1. Run the command to view labels in nodeSelector:

   d8 k get mc sds-local-volume -o=jsonpath={.spec.settings.dataNodes.nodeSelector}
   

   Example output:

   nodeSelector:
     my-custom-label-key: my-custom-label-value
   

2. Check the selectors that the module uses in the d8-sds-local-volume-controller-config secret:

   d8 k -n d8-sds-local-volume get secret d8-sds-local-volume-controller-config -o jsonpath='{.data.config}' | base64 --decode
   

   Example output:

   nodeSelector:
     kubernetes.io/os: linux
     my-custom-label-key: my-custom-label-value
   

   The output should include all labels from the module’s data.nodeSelector settings, as well as kubernetes.io/os: linux.

3. Check the labels on the node:

   d8 k get node <node-name> --show-labels
   

4. Add the missing labels to the node:

   d8 k label node <node-name> my-custom-label-key=my-custom-label-value
   

5. If the labels are present, check for the storage.deckhouse.io/sds-local-volume-node= label on the node. If the label is missing, check the controller status:

   d8 k -n d8-sds-local-volume get po -l app=sds-local-volume-controller
   d8 k -n d8-sds-local-volume logs -l app=sds-local-volume-controller