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Chapter 1. Preparing to deploy OpenShift Container Storage

When you deploy OpenShift Container Storage on OpenShift Container Platform using local storage devices, you can create internal cluster resources. This approach internally provisions base services. Then, all applications can access additional storage classes.

Before you begin the deployment of Red Hat OpenShift Container Storage using local storage, ensure that your resource requirements are met. See requirements for installing OpenShift Container Storage using local storage devices.

After you have addressed the above, follow the below steps in the order given:

1.1. Requirements for installing OpenShift Container Storage using local storage devices

Node requirements

The cluster must consist of at least three OpenShift Container Platform worker nodes with locally attached-storage devices on each of them.

  • Each of the three selected nodes must have at least one raw block device available to be used by OpenShift Container Storage.
  • The devices you use must be empty; the disks must not include physical volumes (PVs), volume groups (VGs), or logical volumes (LVs) remaining on the disk.

See the Resource requirements section in Planning guide.

Arbiter stretch cluster requirements [Technology Preview]

  • You need a minimum of five nodes in three zones. Two zones include two nodes per data-center zone while the third zone includes one node. A master node can be used for the arbiter zone.
  • This solution is designed to be deployed where latencies do not exceed 4 milliseconds round-trip time (RTT) between locations. Contact Red Hat Customer Support if you are planning to deploy with higher latencies.
  • Each node must be pre-labeled with its zone label. To label the nodes use the following command:

    $ oc label nodes <NodeNames> topology.kubernetes.io/zone='<label>'

    For example, you can label the nodes as follows:

    • topology.kubernetes.io/zone=arbiter to master or worker node
    • topology.kubernetes.io/zone=datacenter1 to at least two worker nodes
    • topology.kubernetes.io/zone=datacenter2 to at least two worker nodes

Compact mode requirements [Technology Preview]

OpenShift Container Storage can be installed on a three-node OpenShift compact bare metal cluster, where all the workloads run on three strong master nodes. There are no worker or storage nodes.

Minimum starting node requirements [Technology Preview]

An OpenShift Container Storage cluster will be deployed with minimum configuration when the standard deployment resource requirement is not met. See Resource requirements section in Planning guide.

1.2. Enabling file system access for containers on Red Hat Enterprise Linux based nodes

Deploying OpenShift Container Storage on an OpenShift Container Platform with worker nodes on a Red Hat Enterprise Linux base in a user provisioned infrastructure (UPI) does not automatically provide container access to the underlying Ceph file system.

Note

Skip this step for hosts based on Red Hat Enterprise Linux CoreOS (RHCOS).

Procedure

  1. Log in to the Red Hat Enterprise Linux based node and open a terminal.
  2. For each node in your cluster:

    1. Verify that the node has access to the rhel-7-server-extras-rpms repository.

      # subscription-manager repos --list-enabled | grep rhel-7-server

      If you do not see both rhel-7-server-rpms and rhel-7-server-extras-rpms in the output, or if there is no output, run the following commands to enable each repository.

      # subscription-manager repos --enable=rhel-7-server-rpms
      # subscription-manager repos --enable=rhel-7-server-extras-rpms
    2. Install the required packages.

      # yum install -y policycoreutils container-selinux
    3. Persistently enable container use of the Ceph file system in SELinux.

      # setsebool -P container_use_cephfs on

1.3. Enabling key value backend path and policy in Vault

Prerequisites

  • Administrator access to Vault.
  • Carefully, choose a unique path name as the backend path that follows the naming convention since it cannot be changed later.

Procedure

  1. Enable the Key/Value (KV) backend path in Vault.

    For Vault KV secret engine API, version 1:

    $ vault secrets enable -path=ocs kv

    For Vault KV secret engine API, version 2:

    $ vault secrets enable -path=ocs kv-v2
  2. Create a policy to restrict users to perform a write or delete operation on the secret using the following commands:

    echo '
    path "ocs/*" {
      capabilities = ["create", "read", "update", "delete", "list"]
    }
    path "sys/mounts" {
    capabilities = ["read"]
    }'| vault policy write ocs -
  3. Create a token matching the above policy:

    $ vault token create -policy=ocs -format json