Chapter 2. Preparing to deploy storage cluster with disaster recovery enabled

2.1. Requirements for enabling Metro-DR

  • Ensure that you have at least three OpenShift Container Platform master nodes in three different zones. One master node in each of the three zones.
  • Ensure that you have at least four OpenShift Container Platform worker nodes evenly distributed across the two Data Zones.
  • For stretch cluster on bare metal, use the SSD drive as the root drive for OpenShift Container Platform master nodes.
  • Ensure that each node is pre-labeled with its zone label. For more information, see the Applying topology zone labels to OpenShift Container Platform node section.
  • The Metro-DR solution is designed for deployments where latencies do not exceed 2 ms between zones, with a maximum round-trip time (RTT) of 4 ms. Contact Red Hat Customer Support if you are planning to deploy with higher latencies.
Note

Flexible scaling and Arbiter both cannot be enabled at the same time as they have conflicting scaling logic. With Flexible scaling, you can add one node at a time to your OpenShift Data Foundation cluster. Whereas in an Arbiter cluster, you need to add at least one node in each of the two data zones.

2.2. Applying topology zone labels to OpenShift Container Platform nodes

During a site outage, the zone that has the arbiter function makes use of the arbiter label. These labels are arbitrary and must be unique for the three locations.

For example, you can label the nodes as follows: 

topology.kubernetes.io/zone=arbiter for Master0

topology.kubernetes.io/zone=datacenter1 for Master1, Worker1, Worker2

topology.kubernetes.io/zone=datacenter2 for Master2, Worker3, Worker4

  • To apply the labels to the node: 

    $ oc label node <NODENAME> topology.kubernetes.io/zone=<LABEL>
    <NODENAME>
    Is the name of the node
    <LABEL>
    Is the topology zone label

  • To validate the labels using the example labels for the three zones: 

    $ oc get nodes -l topology.kubernetes.io/zone=<LABEL> -o name
    <LABEL>

    Is the topology zone label

    Alternatively, you can run a single command to see all the nodes with it’s zone. 

    $ oc get nodes -L topology.kubernetes.io/zone

The Metro-DR stretch cluster topology zone labels are now applied to the appropriate OpenShift Container Platform nodes to define the three locations.

Next step

2.3. Installing Local Storage Operator

Install the Local Storage Operator from the Operator Hub before creating Red Hat OpenShift Data Foundation clusters on local storage devices.

Procedure

  1. Log in to the OpenShift Web Console.
  2. Click Operators → OperatorHub.
  3. Type local storage in the Filter by keyword​ box to find the Local Storage Operator from the list of operators and click on it.

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

    1. Update channel as either 4.9 or stable.
    2. Installation mode as A specific namespace on the cluster.
    3. Installed Namespace as Operator recommended namespace openshift-local-storage.
    4. Update approval as Automatic.
  5. Click Install.

Verification steps

  • Verify that the Local Storage Operator shows a green tick indicating successful installation.

2.4. Installing Red Hat OpenShift Data Foundation Operator

You can install Red Hat OpenShift Data Foundation 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.
  • You must have at least four worker nodes evenly distributed across two data centers in the Red Hat OpenShift Container Platform cluster.
  • For additional resource requirements, see Planning your deployment.
Important

  • When you need to override the cluster-wide default node selector for OpenShift Data Foundation, you can use the following command in command-line interface to specify a blank node selector for the openshift-storage namespace (create openshift-storage namespace in this case): 

    $ oc annotate namespace openshift-storage openshift.io/node-selector=
  • Taint a node as infra to ensure only Red Hat OpenShift Data Foundation resources are scheduled on that node. This helps you save on subscription costs. For more information, see How to use dedicated worker nodes for Red Hat OpenShift Data Foundation chapter in the Managing and Allocating Storage Resources guide.

Procedure

  1. Log in to the OpenShift Web Console.
  2. Click Operators → OperatorHub.
  3. Scroll or type OpenShift Data Foundation into the Filter by keyword box to search for the OpenShift Data Foundation Operator.
  4. Click Install.

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

    1. Update Channel as stable-4.9.
    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 selected 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.

  6. Ensure that the Enable option is selected for the Console plugin.
  7. Click Install.

Verification steps

Verify that the OpenShift Data Foundation Operator shows a green tick indicating successful installation.

Next steps