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Chapter 1. Preparing to deploy OpenShift Container Storage

Deploying OpenShift Container Storage on OpenShift Container Platform using dynamic or local storage devices provides you with the option to create internal cluster resources. This will result in the internal provisioning of the base services, which helps to make additional storage classes available to applications.

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

  1. For Red Hat Enterprise Linux based hosts for worker nodes in a user provisioned infrastructure (UPI), enable the container access to the underlying file system. Follow the instructions on enable file system access for containers on Red Hat Enterprise Linux based nodes.

    Note

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

  2. Optional: If you want to enable cluster-wide encryption using an external Key Management System (KMS):

  3. 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.

  4. For deploying using local storage devices, see requirements for installing OpenShift Container Storage using local storage devices. These are not applicable for deployment using dynamic storage devices.

1.1. 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 section 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

1.2. Enabling key value backend path and policy in Vault

Prerequisites

  • Administrator access to Vault.
  • 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

1.3. 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.

For more information, see the Resource requirements section in the Planning guide.

Arbiter stretch cluster requirements [Technology Preview]

In this case, a single cluster is stretched across two zones with a third zone as the location for the arbiter. This is a technology preview feature that is currently intended for deployment in the OpenShift Container Platform on-premises.

For detailed requirements and instructions, see Configuring OpenShift Container Storage for Metro-DR stretch cluster.

Note

You cannot enable both flexible scaling and arbiter as they have conflicting scaling logic. With flexing scaling, you can add one node at a time to the OpenShift Container Storage cluster. Whereas, in an arbiter cluster, you need to add at least one node in each of the 2 data zones.

Minimum starting node requirements [Technology Preview]

An OpenShift Container Storage cluster is deployed with minimum configuration when the standard deployment resource requirement is not met.

For more information, see Resource requirements section in the Planning guide.