Deploying and managing OpenShift Data Foundation on single node OpenShift clusters

Red Hat OpenShift Data Foundation 4.11

Instructions for deploying and managing OpenShift Data Foundation on single node OpenShift clusters.

Red Hat Storage Documentation Team

Abstract

Read this document for instructions regarding installing Red Hat OpenShift Data Foundation Logical Volume Manager Operator on single node OpenShift clusters.
Important
Deploying and managing OpenShift Data Foundation 4.11 on single node OpenShift clusters is a Technology Preview feature. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.
A General Available version of this product (renamed as logical volume manager storage (LVM storage)) is now available. For information, see LVM Storage documentation.

Making open source more inclusive

Red Hat is committed to replacing problematic language in our code, documentation, and web properties. We are beginning with these four terms: master, slave, blacklist, and whitelist. Because of the enormity of this endeavor, these changes will be implemented gradually over several upcoming releases. For more details, see our CTO Chris Wright’s message.

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Preface

Red Hat OpenShift Data Foundation supports deploying OpenShift Data Foundation using the Red Hat OpenShift Data Foundation Logical Volume Manager Operator on single node OpenShift (SNO) clusters. This operator uses the TopoLVM CSI driver to dynamically provision local storage.

Red Hat OpenShift Data Foundation Logical Volume Manager Operator creates thin-provisioned volumes using the Logical Volume Manager and provides dynamic provisioning of block storage on a single node, limited resources SNO cluster.

You can deploy the Red Hat OpenShift Data Foundation Logical Volume Manager Operator on a single node Openshift bare metal or user provisioned infrasturcture cluster and configure it to dynamically provision storage for your workloads.

The operator creates a volume group using all the available unused disks and creates a single thin pool with a size of 90% of the volume group. The remaining 10% of the volume group is left free to enable data recovery by expanding the thin pool when required. You might need to manually perform such recovery.

You can use persistent volume claims (PVCs) and volume snapshots provisioned by the Logical Volume Manager Operator to request storage and create volume snapshots.

The Red Hat OpenShift Data Foundation Logical Volume Manager Operator configures a default overprovisioning limit of 10 to take advantage of the thin-provisioning feature. The total size of the volumes and volume snapshots that can be created on the single node OpenShift clusters is 10 times the size of the thin pool.

You can deploy OpenShift Data Foundation on single node OpenShift clusters using one of the following:

  • Red Hat Advanced Cluster Management for Kubernetes (RHACM)
  • OpenShift Web Console

Chapter 1. Deploying OpenShift Data Foundation on single node OpenShift clusters using RHACM

1.1. Requirements for deploying using RHACM

Before you begin deploying OpenShift Data Foundation Logical Volume Manager Operator on single node Openshift clusters, ensure that the following requirements are met:

  1. You have installed Red Hat Advanced Cluster Management for Kubernetes (RHACM) on an OpenShift cluster. For information, see Red Hat Advanced Cluster Management for Kubernetes: Install.
  2. Every managed SNO cluster has dedicated disks that are used to provision storage.

1.2. Installing the OpenShift Data Foundation Logical Volume Manager Operator using RHACM

The OpenShift Data Foundation Logical Volume Manager Operator is deployed on single node OpenShift (SNO) clusters using Red Hat Advanced Cluster Management for Kubernetes (RHACM). You create a Policy on RHACM that deploys and configures the operator when it is applied to managed clusters which match the selector specified in the PlacementRule. The policy is also applied to clusters that are imported later and satisfy the PlacementRule.

Prerequisites

  • Access to the RHACM cluster using an account with cluster-admin and operator installation permissions.
  • Dedicated disks on each SNO cluster to be used by OpenShift Data Foundation Logical Volume Manager Operator.
Note

Ensure that no other storage provisioner is installed on the SNO cluster. OpenShift Data Foundation Logical Volume Manager Operator should be the only storage provisioner as it uses all available disks on the node.

Procedure

  1. Log in to the RHACM CLI using your OpenShift credentials.

    For more information, see Install Red Hat Advanced Cluster Management for Kubernetes.

  2. Create a namespace in which you will create policies. 

    # oc create ns lvm-policy-ns

  3. Save the following YAML to a file with a name such as policy-lvm-operator.yaml to create a policy. 

    # This policy verifies the installation of the official version of the {product-name-short}
# Logical Volume Manager Operator on the managed clusters.
# If set to "enforce" it installs the operator.
# Used APIs: OLM, ODF-LVMO #https://github.com/operator-framework/operator-lifecycle-manager
# https://github.com/red-hat-storage/lvm-operator

apiVersion: apps.open-cluster-management.io/v1
kind: PlacementRule
metadata:
  name: placement-install-odf-lvm-operator
spec:
  clusterConditions:
  - status: "True"
    type: ManagedClusterConditionAvailable
  clusterSelector:
    matchExpressions:
    - key: vendor
      operator: In
      values:
      - OpenShift
---
apiVersion: policy.open-cluster-management.io/v1
kind: PlacementBinding
metadata:
  name: binding-install-odf-lvm-operator
placementRef:
  apiGroup: apps.open-cluster-management.io
  kind: PlacementRule
  name: placement-install-odf-lvm-operator
subjects:
- apiGroup: policy.open-cluster-management.io
  kind: Policy
  name: install-odf-lvm-operator
---
apiVersion: policy.open-cluster-management.io/v1
kind: Policy
metadata:
  annotations:
    policy.open-cluster-management.io/categories: CM Configuration Management
    policy.open-cluster-management.io/controls: CM-2 Baseline Configuration
    policy.open-cluster-management.io/standards: NIST SP 800-53
  name: install-odf-lvm-operator
spec:
  disabled: false
  remediationAction: enforce
  policy-templates:
  - objectDefinition:
      apiVersion: policy.open-cluster-management.io/v1
      kind: ConfigurationPolicy
      metadata:
        name: install-odf-lvm-operator
      spec:
        object-templates:
        - complianceType: musthave
          objectDefinition:
            apiVersion: v1
            kind: Namespace
            metadata:
              labels:
                openshift.io/cluster-monitoring: "true"
                pod-security.kubernetes.io/enforce: privileged
                pod-security.kubernetes.io/audit: privileged
                pod-security.kubernetes.io/warn: privileged
              name: openshift-storage
        - complianceType: musthave
          objectDefinition:
            apiVersion: operators.coreos.com/v1
            kind: OperatorGroup
            metadata:
              name: openshift-storage-operatorgroup
              namespace: openshift-storage
            spec:
              targetNamespaces:
              - openshift-storage
        - complianceType: musthave
          objectDefinition:
            apiVersion: operators.coreos.com/v1alpha1
            kind: Subscription
            metadata:
              name: odf-lvm-operator
              namespace: openshift-storage
            spec:
              installPlanApproval: Automatic
              name: odf-lvm-operator
              source: redhat-operators
              sourceNamespace: openshift-marketplace
        remediationAction: enforce
        severity: low
  - objectDefinition:
      apiVersion: policy.open-cluster-management.io/v1
      kind: ConfigurationPolicy
      metadata:
        name: odf-lvmcluster
      spec:
        object-templates:
           - complianceType: musthave
             objectDefinition:
               apiVersion: lvm.topolvm.io/v1alpha1
               kind: LVMCluster
               metadata:
                 name: odf-lvmcluster
                 namespace: openshift-storage
               spec:
                 storage:
                   deviceClasses:
                   - name: vg1
                     thinPoolConfig:
                       name: thin-pool-1
                       sizePercent: 90
                       overprovisionRatio: 10
        remediationAction: enforce
        severity: low

  4. Create the policy in the namespace by running the following command: 

    # oc create -f policy-lvm-operator.yaml -n lvm-policy-ns

    where, policy-lvm-operator.yaml is the name of the file to which the policy is saved.

    This creates a Policy, a PlacementRule, and a PlacementBinding in the namespace, lvm-policy-ns. The Policy creates a Namespace, OperatorGroup, Subscription, and LVMCluster resource on the clusters matching the PlacementRule. This deploys the operator on the SNO clusters which match the selection criteria and configures it to set up the required resources to provision storage. The operator uses all the unused disks after installation.

1.3. Uninstalling OpenShift Data Foundation Logical Volume Manager Operator installed using RHACM

To uninstall OpenShift Data Foundation Logical Volume Manager Operator when you have installed the operator using RHACM, you need to delete the ACM policy that you created for deploying and configuring the operator. However, when you delete the ACM policy, the resources that the policy has created are not removed. You need to create additional policies to remove the resources.

As the resources that are created are not removed when you delete the policy, you need to perform the following steps:

  • Remove all the PVCs and volume snapshots provisioned by the Logical Volume Manager Operator.
  • Remove the LVMCluster resources to clean up the Logical Volume Manager resources created on the disks.
  • Create an additional policy to uninstall the operator.

Prerequisites

  • Ensure that the following are deleted before deleting the policy:

    • All the applications on the managed clusters that are using the storage provisioned by the OpenShift Data Foundation Logical Volume Manager Operator.
    • Persistent volume claims (PVCs) and persistent volumes (PVs) provisioned using the OpenShift Data Foundation Logical Volume Manager Operator.
    • All volume snapshots provisioned by the OpenShift Data Foundation Logical Volume Manager Operator.
  • Ensure that no logical volume resources exist by using the oc get logicalvolume command.
  • Access to the RHACM cluster using an account with cluster-admin role.

Procedure

  1. In the OpenShift command-line interface, delete the ACM policy that you created for deploying and configuring the OpenShift Data Foundation Logical Volume Manager Operator on the hub cluster by using the following command: 

    # oc delete -f policy-lvm-operator.yaml -n lvm-policy-ns

  2. Save the following YAML to a file with a name such as odf-lvmcluster-deletion.yaml to create a policy for removing the LVMCluster. This enables the operator to clean up all the Logical Volume Manager resources that it created on the cluster. 

    apiVersion: policy.open-cluster-management.io/v1
kind: Policy
metadata:
  name: policy-lvmcluster-delete
  annotations:
    policy.open-cluster-management.io/standards: NIST SP 800-53
    policy.open-cluster-management.io/categories: CM Configuration Management
    policy.open-cluster-management.io/controls: CM-2 Baseline Configuration
spec:
  remediationAction: enforce
  disabled: false
  policy-templates:
    - objectDefinition:
        apiVersion: policy.open-cluster-management.io/v1
        kind: ConfigurationPolicy
        metadata:
          name: policy-lvmcluster-removal
        spec:
          remediationAction: enforce # the policy-template spec.remediationAction is overridden by the preceding parameter value for spec.remediationAction.
          severity: low
          object-templates:
            - complianceType: mustnothave
              objectDefinition:
                kind: LVMCluster
                apiVersion: lvm.topolvm.io/v1alpha1
                metadata:
                  name: odf-lvmcluster
                  namespace: openshift-storage # must have namespace 'openshift-storage'
---
apiVersion: policy.open-cluster-management.io/v1
kind: PlacementBinding
metadata:
 name: binding-policy-lvmcluster-delete
placementRef:
 apiGroup: apps.open-cluster-management.io
 kind: PlacementRule
 name: placement-policy-lvmcluster-delete
subjects:
 - apiGroup: policy.open-cluster-management.io
   kind: Policy
   name: policy-lvmcluster-delete
---
apiVersion: apps.open-cluster-management.io/v1
kind: PlacementRule
metadata:
 name: placement-policy-lvmcluster-delete
spec:
 clusterConditions:
   - status: 'True'
     type: ManagedClusterConditionAvailable
 clusterSelector:
   matchExpressions:
     - key: vendor
       operator: In
       values:
         - OpenShift

  3. Create the policy by running the following command: 

    # oc create -f odf-lvmcluster-deletion.yaml -n lvm-policy-ns

  4. Save the following YAML to a file with a name such as check-odf-lvmcluster-deletion.yaml to create a policy to check if the LVMCluster CR has been removed. 

    apiVersion: policy.open-cluster-management.io/v1
kind: Policy
metadata:
  name: policy-lvmcluster-inform
  annotations:
    policy.open-cluster-management.io/standards: NIST SP 800-53
    policy.open-cluster-management.io/categories: CM Configuration Management
    policy.open-cluster-management.io/controls: CM-2 Baseline Configuration
spec:
  remediationAction: inform
  disabled: false
  policy-templates:
    - objectDefinition:
        apiVersion: policy.open-cluster-management.io/v1
        kind: ConfigurationPolicy
        metadata:
          name: policy-lvmcluster-removal-inform
        spec:
          remediationAction: inform # the policy-template spec.remediationAction is overridden by the preceding parameter value for spec.remediationAction.
          severity: low
          object-templates:
            - complianceType: mustnothave
              objectDefinition:
                kind: LVMCluster
                apiVersion: lvm.topolvm.io/v1alpha1
                metadata:
                  name: odf-lvmcluster
                  namespace: openshift-storage # must have namespace 'openshift-storage'
---
apiVersion: policy.open-cluster-management.io/v1
kind: PlacementBinding
metadata:
 name: binding-policy-lvmcluster-check
placementRef:
 apiGroup: apps.open-cluster-management.io
 kind: PlacementRule
 name: placement-policy-lvmcluster-check
subjects:
 - apiGroup: policy.open-cluster-management.io
   kind: Policy
   name: policy-lvmcluster-inform
---
apiVersion: apps.open-cluster-management.io/v1
kind: PlacementRule
metadata:
 name: placement-policy-lvmcluster-check
spec:
 clusterConditions:
   - status: 'True'
     type: ManagedClusterConditionAvailable
 clusterSelector:
   matchExpressions:
     - key: vendor
       operator: In
       values:
         - OpenShift

  5. Create the policy by running the following command: 

    # oc create -f check-odf-lvmcluster-deletion.yaml -n lvm-policy-ns

  6. Check the policy status. 

    # oc get policy -n lvm-policy-ns
NAME                       REMEDIATION ACTION   COMPLIANCE STATE   AGE
policy-lvmcluster-delete   enforce              Compliant          15m
policy-lvmcluster-inform   inform               Compliant          15m

  7. After both the policies are compliant, save the following YAML to a file with a name such as odf-lvm-operator-remove-policy.yaml to create a policy to uninstall the OpenShift Data Foundation Logical Volume Manager Operator. 

    apiVersion: apps.open-cluster-management.io/v1
kind: PlacementRule
metadata:
  name: placement-uninstall-odf-lvm-operator
spec:
  clusterConditions:
  - status: "True"
    type: ManagedClusterConditionAvailable
  clusterSelector:
    matchExpressions:
    - key: vendor
      operator: In
      values:
      - OpenShift
---
apiVersion: policy.open-cluster-management.io/v1
kind: PlacementBinding
metadata:
  name: binding-uininstall-odf-lvm-operator
placementRef:
  apiGroup: apps.open-cluster-management.io
  kind: PlacementRule
  name: placement-uninstall-odf-lvm-operator
subjects:
- apiGroup: policy.open-cluster-management.io
  kind: Policy
  name: uninstall-odf-lvm-operator
---
apiVersion: policy.open-cluster-management.io/v1
kind: Policy
metadata:
  annotations:
    policy.open-cluster-management.io/categories: CM Configuration Management
    policy.open-cluster-management.io/controls: CM-2 Baseline Configuration
    policy.open-cluster-management.io/standards: NIST SP 800-53
  name: uninstall-odf-lvm-operator
spec:
  disabled: false
  policy-templates:
  - objectDefinition:
      apiVersion: policy.open-cluster-management.io/v1
      kind: ConfigurationPolicy
      metadata:
        name: uninstall-odf-lvm-operator
      spec:
        object-templates:
        - complianceType: mustnothave
          objectDefinition:
            apiVersion: v1
            kind: Namespace
            metadata:
              name: openshift-storage
        - complianceType: mustnothave
          objectDefinition:
            apiVersion: operators.coreos.com/v1
            kind: OperatorGroup
            metadata:
              name: openshift-storage-operatorgroup
              namespace: openshift-storage
            spec:
              targetNamespaces:
              - openshift-storage
        - complianceType: mustnothave
          objectDefinition:
            apiVersion: operators.coreos.com/v1alpha1
            kind: Subscription
            metadata:
              name: odf-lvm-operator
              namespace: openshift-storage
            spec:
              installPlanApproval: Automatic
              name: odf-lvm-operator
              source: redhat-operators
              sourceNamespace: openshift-marketplace
        remediationAction: enforce
        severity: low
  - objectDefinition:
      apiVersion: policy.open-cluster-management.io/v1
      kind: ConfigurationPolicy
      metadata:
        name: policy-remove-lvm-operator-crds
      spec:
        object-templates:
        - complianceType: mustnothave
          objectDefinition:
            apiVersion: apiextensions.k8s.io/v1
            kind: CustomResourceDefinition
            metadata:
              name: logicalvolumes.topolvm.cybozu.com
        - complianceType: mustnothave
          objectDefinition:
            apiVersion: apiextensions.k8s.io/v1
            kind: CustomResourceDefinition
            metadata:
              name: lvmclusters.lvm.topolvm.io
        - complianceType: mustnothave
          objectDefinition:
            apiVersion: apiextensions.k8s.io/v1
            kind: CustomResourceDefinition
            metadata:
              name: lvmvolumegroupnodestatuses.lvm.topolvm.io
        - complianceType: mustnothave
          objectDefinition:
            apiVersion: apiextensions.k8s.io/v1
            kind: CustomResourceDefinition
            metadata:
              name: lvmvolumegroups.lvm.topolvm.io
        remediationAction: enforce
        severity: high

  8. Create the policy by running the following command: 

    # oc create -f odf-lvm-operator-remove-policy.yaml -ns lvm-policy-ns

Chapter 2. Deploying OpenShift Data Foundation on single node OpenShift clusters using OpenShift Web Console

2.1. Installing Red Hat OpenShift Data Foundation Logical Volume Manager Operator using OpenShift Web Console

You can install Red Hat OpenShift Data Foundation Logical Volume Manager Operator using the Red Hat OpenShift Container Platform Operator Hub.

Prerequisites

  • Access to an OpenShift Container Platform cluster using an account with cluster-admin and Operator installation permissions.
Note

Ensure that no other storage provisioner is installed on the SNO cluster. OpenShift Data Foundation Logical Volume Manager Operator should be the only storage provisioner as it uses all available disks on the node.

Procedure

  1. Log in to the OpenShift Web Console.
  2. Click Operators → OperatorHub.
  3. Scroll or type ODF LVM Operator into the Filter by keyword box to find the ODF LVM Operator.
  4. Click Install.

  5. Set the following options on the Install Operator page:

    1. Update Channel as stable-4.11.
    2. Installation Mode as A specific namespace on the cluster.
    3. Installed Namespace as Operator recommended namespace openshift-storage. If Namespace openshift-storage does not exist, it is created during the operator installation.

    4. Select Approval Strategy as Automatic or Manual.

      If you select Automatic updates, then the Operator Lifecycle Manager (OLM) automatically upgrades the running instance of your Operator without any intervention.

      If you select Manual updates, then the OLM creates an update request. As a cluster administrator, you must then manually approve that update request to update the Operator to a newer version.

    5. Click Install.

Verification steps

  • Verify that the ODF LVM Operator shows a green tick indicating successful installation.

2.2. Creating OpenShift Data Foundation Logical Volume Manager cluster

Create Logical Volume Manager cluster after you install the OpenShift Data Foundation Logical Volume Manager operator.

Prerequisites

  • The OpenShift Data Foundation Logical Volume Manager operator must be installed from the Operator Hub.

Procedure

  1. In the OpenShift Web Console, click Operators → Installed Operators to view all the installed operators.

    Ensure that the Project selected is openshift-storage.

  2. Click on the ODF LVM operator, and then click Create instance under LVMCluster.
  3. In the Create LVMCluster page, select either Form view or YAML view.
  4. Enter a name for the cluster.
  5. Click Create.

Verification Steps

  1. Click Storage → Storage Classes from the left pane of the OpenShift Web Console.
  2. Verify that the odf-lvm-<device-class-name> storage class is created with the ODF LVM cluster creation. By default, vg1 is the device-class-name.

2.3. Uninstalling OpenShift Data Foundation Logical Volume Manager Operator installed using OpenShift Web Console

Prerequisites

  • Ensure that the following are deleted before deleting the policy:

    • All the applications on the managed clusters that are using the storage provisioned by the OpenShift Data Foundation Logical Volume Manager Operator.
    • Persistent volume claims (PVCs) and persistent volumes (PVs) provisioned using the OpenShift Data Foundation Logical Volume Manager Operator.
    • All volume snapshots provisioned by the OpenShift Data Foundation Logical Volume Manager Operator.
  • Ensure that no logical volume resources exist by using the oc get logicalvolume command.

Procedure

  1. Select the project openshift-storage. 

    $ oc project openshift-storage

  2. Display the pods. 

    $ oc get pods
NAME                                               READY   STATUS    RESTARTS      AGE
lvm-operator-controller-manager-54df65b5c4-n7bhb   3/3     Running   1 (45h ago)   7d2h
topolvm-controller-645cb47cd4-kskqb                5/5     Running   5 (45h ago)   7d3h
topolvm-node-7bqxp                                 4/4     Running   0             7d3h
vg-manager-hwmg2                                   1/1     Running   0             7d

  3. Display the lvmcluster. 

    $ oc get lvmcluster
NAME             AGE
odf-lvmcluster   7d3h

  4. Delete the lvmcluster. 

    $ oc delete lvmcluster odf-lvmcluster
lvmcluster.lvm.topolvm.io "odf-lvmcluster" deleted

  5. Verify the deletion by displaying the lvmcluster. 

    $ oc get lvmcluster
No resources found in openshift-storage namespace.

  6. Wait until there is only the lvm-operator pod running. 

    $ oc get pods
NAME                                               READY   STATUS    RESTARTS      AGE
lvm-operator-controller-manager-54df65b5c4-n7bhb   3/3     Running   1 (45h ago)   7d2h

  7. Change the project to default. 

    $ oc project default

  8. Delete the project openshift-storage. 

    $ oc delete project openshift-storage

Chapter 3. Provisioning storage using Logical Volume Manager Operator

You can provision persistent volume claims (PVCs) using the storage class that gets created during the operator installation. You can provision block and file PVCs, however, the storage is allocated only when a pod that uses the PVC is created.

Note

The Red Hat OpenShift Data Foundation Logical Volume Manager Operator provisions PVCs in units of 1 GiB. The requested storage is rounded up to the nearest GiB.

Procedure

  1. Identify the StorageClass that is created when Red Hat OpenShift Data Foundation Logical Volume Manager Operator is deployed.

    The StorageClass name is in the format, odf-lvm-<device-class-name>. device-class-name is the name of the device class that you provided in the LVMCluster of the policy YAML. For example, if the deviceClass has the name as vg1, then the storageClass name is odf-lvm-vg1.

  2. Save the following YAML to a file with a name such as odf-lvm-storage-class.yaml to create a PVC where the application requires storage. 

    # Sample YAML to create a PVC
# block pvc
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: lvm-block-1
  namespace: default
spec:
  accessModes:
    - ReadWriteOnce
  volumeMode: Block
  resources:
    requests:
      storage: 10Gi
  storageClassName: odf-lvm-vg1
---
# file pvc
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: lvm-file-1
  namespace: default
spec:
  accessModes:
    - ReadWriteOnce
  volumeMode: Filesystem
  resources:
    requests:
      storage: 10Gi
  storageClassName: odf-lvm-vg1

  3. Create the policy by running the following command: 

    # oc create -f odf-lvm-storage-class.yaml -ns lvm-policy-ns

    The PVCs that are created will remain in pending state until you deploy the pods that use them.

Chapter 4. Monitoring the OpenShift Data Foundation Logical Volume Manager Operator

When the OpenShift Data Foundation Logical Volume Manager Operator is installed using the OpenShift Web Console, you can monitor the cluster using the Block and File dashboard in the console by default. However, when you use RHACM to install the OpenShift Data Foundation Logical Volume Manager Operator, you need to configure the RHACM Observability to monitor the all the SNO cluster from one place.

You can monitor the OpenShift Data Foundation Logical Volume Manager Operator by viewing the metrics exported by the operator on the RHACM dashboards and the alerts that are triggered. Enable RHACM Observability as described in the Observability guide.

Metrics
topolvm_thinpool_data_percent
topolvm_thinpool_metadata_percent
topolvm_thinpool_size_bytes
Note

Metrics are updated every 10 minutes or when there is a change in the thin-pool, such as a new logical volume creation.

Alerts
When the thin pool and volume group are filled up, further operations fail and might lead to data loss. The Logical Volume Manager Operator sends the following alerts the usage of the thin pool and volume group crosses certain value:

Table 4.1. Alerts for Logical Volume Manager cluster in Red Hat Advanced Cluster Management for Kubernetes

AlertDescription

VolumeGroupUsageAtThresholdNearFull

This alert is triggered when both the volume group and thin pool utilization cross 75% on nodes. Data deletion or volume group expansion is required.

VolumeGroupUsageAtThresholdCritical

This alert is triggered when both the volume group and thin pool utilization cross 85% on nodes.VolumeGroup is critically full. Data deletion or volume group expansion is required.

ThinPoolDataUsageAtThresholdNearFull

This alert is triggered when the thin pool data utilization in the volume group crosses 75% on nodes. Data deletion or thin pool expansion is required.

ThinPoolDataUsageAtThresholdCritical

This alert is triggered when the thin pool data utilization in the volume group crosses 85% on nodes. Data deletion or thin pool expansion is required.

ThinPoolMetaDataUsageAtThresholdNearFull

This alert is triggered when the thin pool metadata utilization in the volume group crosses 75% on nodes. Data deletion or thin pool expansion is required.

ThinPoolMetaDataUsageAtThresholdCritical

This alert is triggered when the thin pool metadata utilization in the volume group crosses 85% on nodes. Data deletion or thin pool expansion is required.

Chapter 5. Volume snapshots for single node OpenShift

You can take volume snapshots of persistent volumes (PVs) that are provisioned by the OpenShift Data Foundation Logical Volume Manager Operator. You can also create volume snapshots of the cloned volumes. Volume snapshots help you to:

  • Back up your application data (volume snapshots are not backups)
  • Revert to a state at which the volume snapshot was taken

You can create volume snapshots based on the available capacity of the thin pool and overprovisioning limits. The Red Hat OpenShift Data Foundation Logical Volume Manager Operator creates a VolumeSnapshotClass with the name odf-lvm-<deviceclass-name>.

5.1. Creating volume snapshots in single node openshift

Prerequisites

  • For a consistent snapshot, ensure that the PVC is in Bound state. Also, ensure that all the I/O to the PVC is stopped before taking the snapshot.

Procedure

  1. Save the following YAML to a file with a name such as odf-lvm-vol-snapshot.yaml to create a policy for volume snapshot. 

    # Sample YAML to create a volume snapshot

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
    name: lvm-block-1-snap
 spec:
     volumeSnapshotClassName: odf-lvm-vg1
     source:
        persistentVolumeClaimName: lvm-block-1

  2. Create the policy by running the following command: 

    # oc create -f odf-lvm-vol-snapshot.yaml -ns lvm-policy-ns

    A read only copy of the PVC is created as a volume snapshot.

5.2. Restoring volume snapshots in single node openshift

When you restore a volume snapshot, a new Persistent Volume Claim (PVC) gets created. The restored PVC is independent of the volume snapshot and the source PVC.

Prerequisites

  • The storage class must be the same as that of the source PVC.
  • The size of the requested PVC must be the same as that of the source volume of the snapshot.

Procedure

  1. Identify the storage class name of the source PVC and volume snapshot name.

  2. Save the following YAML to a file with a name such as odf-lvm-vol-restore.yaml to restore the snapshot. 

    # Sample YAML to restore a PVC.

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: lvm-block-1-restore
spec:
  accessModes:
 - ReadWriteOnce
  volumeMode: Block
  Resources:
    Requests:
      storage: 2Gi
  storageClassName: odf-lvm-vg1
  dataSource:
    name: lvm-block-1-snap
    kind: VolumeSnapshot
    apiGroup: snapshot.storage.k8s.io

  3. Create the policy by running the following command: 

    # oc create -f odf-lvm-vol-restore.yaml -ns lvm-policy-ns

5.3. Deleting volume snapshots in single node openshift

Procedure

  • To delete the volume snapshot, delete the volume snapshot resource. 

    oc delete volumesnapshot <volume-snapshot-name> -n <namespace>
    Note

    When you delete a persistent volume claim (PVC), the snapshots of the PVC are not deleted.

  • To delete the restored volume snapshot, delete the PVC that was created to restore the volume snapshot. 
oc delete pvc <pvc-name> -n <namespace>

Chapter 6. Volume cloning for single node OpenShift

A clone is a duplicate of an existing storage volume that can be used like any standard volume. You create a clone of a volume to make a point in time copy of the data. A persistent volume claim (PVC) cannot be cloned with a different size.

6.1. Creating volume clones in single node openshift

Prerequisites

  • Ensure that the source PVC is in Bound state and not in use.
  • Ensure that the StorageClass is the same as that of the parent.

Procedure

  1. Identify the storage class of the source PVC.

  2. Save the following YAML to a file with a name such as odf-lvm-vol-clone.yaml to create a volume clone. 

    # Sample YAML to clone a volume
# pvc-clone.yaml
apiVersion: v1
kind: PersistentVolumeClaim
Metadata:
  name: lvm-block-1-clone
Spec:
  storageClassName: odf-lvm-vg1
  dataSource:
    name: lvm-block-1
    kind: PersistentVolumeClaim
  accessModes:
   - ReadWriteOnce
  volumeMode: Block
  Resources:
    Requests:
      storage: 2Gi
The cloned PVC has write access.
  3. Create the policy by running the following command: 
# oc create -f odf-lvm-vol-clone.yaml -ns lvm-policy-ns

6.2. Deleting cloned volumes in single node openshift

Procedure

  • To delete the cloned volume, you can delete the cloned PVC. 
oc delete pvc <clone-pvc-name> -n <namespace>