Hyperdisk high availability on GKE

Google Cloud Compute Infrastructure
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1

I have 2 nodes spread across 2 zones, where I run my deployments twice as a failover mechanism. In my nodes I have 3 pods that require access to a disk. All works well with a single node, but now 2 nodes must access the disk with read and write access, and I read this is possible with a high availability hyperdisk. I have been trying to do so by following this guide:

I changed the access mode from “ReadWriteOnce” to “ReadWriteMany”, as it says it’s supported. However, when I try to mount this disk, I get this message in the events:

failed to provision volume with StorageClass “balanced-ha-storage”: rpc error: code = InvalidArgument desc = VolumeCapabilities is invalid: specified multi writer with mount access type

I can’t figure out how to get this done, any help would be much appreciated!

1 Like
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Hi djst3rios,

Based on the Internal bug, this is classified as a documentation issue. In the meantime, to successfully provision volumes in RWX mode, you must specify volumeMode: Block

Here’s an example configuration:

kind: PersistentVolumeClaim

apiVersion: v1

metadata:

  name: podpvc

spec:

  accessModes:

  - ReadWriteMany

  volumeMode: Block # <<<<<<

  storageClassName: balanced-ha-storage

  resources:

    requests:

      storage: 20Gi

Additionally,since Pods are consuming a volume in Block mode, you should use the volumeDevcies configuration instead of volumeMounts. Here’s an

Summary

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sample configuration:

apiVersion: apps/v1

kind: Deployment

metadata:

  name: web-server-deployment

  labels:

    app: nginx

spec:

  replicas: 1

  selector:

    matchLabels:

      app: nginx

  template:

    metadata:

      labels:

        app: nginx

    spec:

      containers:

      - name: nginx

        image: nginx

        volumeDevices: # <<<<<<<<

        - mountPath: /dev/my-device

          name: mypvc

      volumes:

      - name: mypvc

        persistentVolumeClaim:

          claimName: podpvc

          readOnly: false
1 Like
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Thank you for your response! I have one more question regarding this, does GKE actually support this kind of disk? It seems it requires a clustered file system such as OCFS2, VMFS and GFS2, which doesn’t seem to be supported by GKE right now.