Chapter 3. Scaling storage capacity of AWS OpenShift Data Foundation cluster

To scale the storage capacity of your configured Red Hat OpenShift Data Foundation worker nodes on AWS cluster, you can increase the capacity by adding three disks at a time. Three disks are needed since OpenShift Data Foundation uses a replica count of 3 to maintain the high availability. So the amount of storage consumed is three times the usable space.

Note

Usable space may vary when encryption is enabled or replica of two pools are being used.

3.1. Scaling up storage capacity on a cluster

To increase the storage capacity in a dynamically created storage cluster on an user-provisioned infrastructure, you can add storage capacity and performance to your configured Red Hat OpenShift Data Foundation worker nodes.

Prerequisites

  • You have administrative privilege to the OpenShift Container Platform Console.
  • You have a running OpenShift Data Foundation Storage Cluster.
  • The disk should be of the same size and type as used during initial deployment.

Procedure

  1. Log in to the OpenShift Web Console.
  2. Click Operators → Installed Operators.
  3. Click OpenShift Data Foundation Operator.

  4. Click the Storage Systems tab.

    1. Click the Action Menu (⋮) on the far right of the storage system name to extend the options menu.
    2. Select Add Capacity from the options menu.
    3. Select the Storage Class. Choose the storage class which you wish to use to provision new storage devices.
    4. Click Add.
  5. To check the status, navigate to Storage → Data Foundation and verify that Storage System in the Status card has a green tick.

Verification steps

  • Verify the Raw Capacity card.

    1. In the OpenShift Web Console, click Storage → Data Foundation.
    2. In the Status card of the Overview tab, click Storage System and then click the storage system link from the pop up that appears.

    3. In the Block and File tab, check the Raw Capacity card.

      Note that the capacity increases based on your selections.

      Note

      The raw capacity does not take replication into account and shows the full capacity.

  • Verify that the new OSDs and their corresponding new Persistent Volume Claims (PVCs) are created.

    • To view the state of the newly created OSDs:

      1. Click Workloads → Pods from the OpenShift Web Console.

      2. Select openshift-storage from the Project drop-down list.

        Note

        If the Show default projects option is disabled, use the toggle button to list all the default projects.

    • To view the state of the PVCs:

      1. Click Storage → Persistent Volume Claims from the OpenShift Web Console.

      2. Select openshift-storage from the Project drop-down list.

        Note

        If the Show default projects option is disabled, use the toggle button to list all the default projects.

  • Optional: If cluster-wide encryption is enabled on the cluster, verify that the new OSD devices are encrypted.

    1. Identify the nodes where the new OSD pods are running. 

      $ oc get -n openshift-storage -o=custom-columns=NODE:.spec.nodeName pod/<OSD-pod-name>
      <OSD-pod-name>

      Is the name of the OSD pod.

      For example: 

      $ oc get -n openshift-storage -o=custom-columns=NODE:.spec.nodeName pod/rook-ceph-osd-0-544db49d7f-qrgqm

      Example output: 

      NODE
compute-1

    2. For each of the nodes identified in the previous step, do the following:

      1. Create a debug pod and open a chroot environment for the selected hosts. 

        $ oc debug node/<node-name>
        <node-name>

        Is the name of the node. 

        $ chroot /host

      2. Check for the crypt keyword beside the ocs-deviceset names. 

        $ lsblk
Important

Cluster reduction is supported only with the Red Hat Support Team’s assistance.

3.2. Scaling out storage capacity on a AWS cluster

OpenShift Data Foundation is highly scalable. It can be scaled out by adding new nodes with required storage and enough hardware resources in terms of CPU and RAM. Practically there is no limit on the number of nodes which can be added but from the support perspective 2000 nodes is the limit for OpenShift Data Foundation.

Scaling out storage capacity can be broken down into two steps

  • Adding new node
  • Scaling up the storage capacity
Note

OpenShift Data Foundation does not support heterogeneous OSD/Disk sizes.

3.2.1. Adding a node

You can add nodes to increase the storage capacity when existing worker nodes are already running at their maximum supported OSDs or there are not enough resources to add new OSDs on the existing nodes. It is always recommended to add nodes in the multiple of three, each of them in different failure domains.

While we recommend adding nodes in the multiple of three, you still get the flexibility of adding one node at a time in the flexible scaling deployment. Refer to the Knowledgebase article Verify if flexible scaling is enabled.

Note

OpenShift Data Foundation does not support heterogeneous disk size and types. The new nodes to be added should have the disk of the same type and size which was used during OpenShift Data Foundation deployment.

3.2.1.1. Adding a node to an installer-provisioned infrastructure

Prerequisites

  • You have administrative privilege to the OpenShift Container Platform Console.
  • You have a running OpenShift Data Foundation Storage Cluster.

Procedure

  1. Navigate to Compute → Machine Sets.

  2. On the machine set where you want to add nodes, select Edit Machine Count.

    1. Add the amount of nodes, and click Save.
    2. Click Compute → Nodes and confirm if the new node is in Ready state.

  3. Apply the OpenShift Data Foundation label to the new node.

    1. For the new node, click Action menu (⋮) → Edit Labels.
    2. Add cluster.ocs.openshift.io/openshift-storage, and click Save.
Note

It is recommended to add 3 nodes, one each in different zones. You must add 3 nodes and perform this procedure for all of them.

Verification steps

  1. Execute the following command the terminal and verify that the new node is present in the output: 

    $ oc get nodes --show-labels | grep cluster.ocs.openshift.io/openshift-storage= |cut -d' ' -f1

  2. On the OpenShift web console, click Workloads → Pods, confirm that at least the following pods on the new node are in Running state:

    • csi-cephfsplugin-*
    • csi-rbdplugin-*

3.2.1.2. Adding a node to an user-provisioned infrastructure

Prerequisites

  • You have administrative privilege to the OpenShift Container Platform Console.
  • You have a running OpenShift Data Foundation Storage Cluster.

Procedure

  1. Depending on the type of infrastructure, perform the following steps:

    1. Get a new machine with the required infrastructure. See Platform requirements.
    2. Create a new OpenShift Container Platform worker node using the new machine.

  2. Check for certificate signing requests (CSRs) that are in Pending state. 

    $ oc get csr

  3. Approve all the required CSRs for the new node. 

    $ oc adm certificate approve <Certificate_Name>
    <Certificate_Name>
    Is the name of the CSR.
  4. Click Compute → Nodes, confirm if the new node is in Ready state.

  5. Apply the OpenShift Data Foundation label to the new node using any one of the following:

    From User interface
    1. For the new node, click Action Menu (⋮) → Edit Labels.
    2. Add cluster.ocs.openshift.io/openshift-storage, and click Save.
    From Command line interface

    • Apply the OpenShift Data Foundation label to the new node. 

      $ oc label node <new_node_name> cluster.ocs.openshift.io/openshift-storage=""
      <new_node_name>
      Is the name of the new node.

Verification steps

  1. Execute the following command the terminal and verify that the new node is present in the output: 

    $ oc get nodes --show-labels | grep cluster.ocs.openshift.io/openshift-storage= |cut -d' ' -f1

  2. On the OpenShift web console, click Workloads → Pods, confirm that at least the following pods on the new node are in Running state:

    • csi-cephfsplugin-*
    • csi-rbdplugin-*

3.2.2. Scaling up storage capacity

To scale up storage capacity, see Scaling up storage by adding capacity.