PersistentVolumeClaim (PVC) requirements

You can use Kubernetes to manage several types of storage used by containers. For BMC Helix, cluster nodes must have access to block storage that is made available to Kubernetes as a Persistent Volume (PV). Claims of reserved memory are then allocated to containers as a Persistent Volume Claim (PVC).

You can configure PersistentVolume and PersistentVolumeClaim in several access modes. The access mode dictates how many nodes or pods can mount and interact with the volume. The following access modes are available:

  • ReadWriteOnce: The volume can be mounted as read-write only by a single node. Multiple pods can use this volume if they are running on the node.
  • ReadWriteOncePod: The volume can be mounted as read-write by multiple nodes. However, only a single Pod can make use of the volume or claim.
  • ReadOnlyMany: The volume can be mounted as read-only by more than one node; for example, NFS.
  • ReadWriteMany: The volume can be mounted as read-write by more than one node; for example, NFS.

BMC Helix makes use of the ReadWriteOnce and ReadWriteMany access modes.

Important

BMC supports a Bring-Your-Own-Storage class for Kubernetes persistent volumes. Your storage class for the Kubernetes persistent volumes must support volume expansion and dynamic provisioning.



PVC requirements for BMC Helix Platform

Important

If you are using VMWare Tanzu to manage your Kubernetes cluster, note the following points:

  • The VMWare NFS storage class provider does not support the ReadWriteMany mode. Refer to the following link to know about the NFS storage class provider you can use instead of the out-of-the-box provider:
    https://core.vmware.com/blog/using-readwritemany-volumes-tkg-clusters

  • The default PVC has root only permissions. Ensure that you are mapping with a user who can read or write to the default PVC share, or enable no_root_squash option. For information about this, see https://serverfault.com/questions/1089557/what-does-the-no-all-squash-option-do-in-nfs-exports.

    Expand to see the sample installation
    [root@control1 nfs-tanzu-rwm-support]# more helm-add-nfs.sh
    helm repo add nfs-subdir-external-provisioner https://kubernetes-sigs.github.io/nfs-subdir-external-provisioner
    helm repo update
    kubectl create namespace infra
    helm install nfs-subdir-external-provisioner --namespace infra nfs-subdir-external-provisioner/nfs-subdir-external-prov
    isioner -f /root/_ade/nfs-tanzu-rwm-support/values.yaml
    [root@control1 nfs-tanzu-rwm-support]#

    For more information, see https://kubernetes-sigs.github.io/nfs-subdir-external-provisioner.


PVC requirements for BMC Helix Operations Management

The following PVC requirements for BMC Helix Operations Management are in addition to the requirements stated for BMC Helix Platform.


PVC requirements for BMC Helix Continuous Optimization

The following PVC requirements for BMC Helix Continuous Optimization are in addition to the requirements stated for BMC Helix Platform.

 

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