3.2. Environment Requirements

The requirements for Red Hat Enterprise Linux Atomic Host, Red Hat OpenShift Container Platform, Red Hat Enterprise Linux, and Red Hat Gluster Storage is described in this section. A Red Hat Gluster Storage Container Native with OpenShift Container Platform environment consists of Red Hat OpenShift Container Platform installed on Red Hat Enterprise Linux Atomic Host or Red Hat Enterprise Linux.

3.2.1. Installing Red Hat Gluster Storage Container Native with OpenShift Container Platform on Red Hat Enterprise Linux 7 based OpenShift Container Platform Cluster

This section describes the procedures to install Red Hat Gluster Storage Container Native with OpenShift Container Platform on Red Hat Enterprise Linux 7 based OpenShift Container Platform 3.5.

3.2.1.1. Setting up the Openshift Master as the Client

You can use the OpenShift Master as a client to execute the oc commands across the cluster when installing OpenShift. Generally, this is setup as a non-scheduled node in the cluster. This is the default configuration when using the OpenShift installer. You can also choose to install their client on their local machine to access the cluster remotely. For more information, see https://access.redhat.com/documentation/en/openshift-container-platform/3.5/single/cli-reference/#installing-the-cli.
Subscribe to the Red Hat Gluster Storage repository

This enables you to install the heketi client packages which are required to setup the client for Red Hat Gluster Storage Container Native with OpenShift Container Platform.

# subscription-manager repos --enable=rh-gluster-3-for-rhel-7-server-rpms
# yum install cns-deploy heketi-client

3.2.1.2. Setting up the Red Hat Enterprise Linux 7 Client for Installing Red Hat Gluster Storage Container Native with OpenShift Container Platform

To set up the Red Hat Enterprise Linux 7 client for installing Red Hat Gluster Storage Container Native with OpenShift Container Platform, perform the following steps:
Subscribe to the Red Hat Gluster Storage repository

This enables you to install the heketi client packages which are required to setup the client for Red Hat Gluster Storage Container Native with OpenShift Container Platform.

# subscription-manager repos --enable=rh-gluster-3-for-rhel-7-server-rpms
# yum install cns-deploy heketi-client
Subscribe to the OpenShift Container Platform 3.5 repository

If you are using OpenShift Container Platform 3.5, subscribe to 3.5 repository to enable you to install the Openshift client packages

# subscription-manager repos --enable=rhel-7-server-ose-3.5-rpms --enable=rhel-7-server-rpms
# yum install atomic-openshift-clients
# yum install atomic-openshift

3.2.2. Installing Red Hat Gluster Storage Container Native with OpenShift Container Platform on Red Hat Enterprise Linux Atomic Host OpenShift Container Platform Cluster

Red Hat Enterprise Linux Atomic host does not support the installation of additional RPMs. Hence, an external client is required on Red Hat Enterprise Linux to install the required packages. To set up the client for Red Hat Enterprise Linux Atomic Host based installations, refer Section 3.2.1.2, “Setting up the Red Hat Enterprise Linux 7 Client for Installing Red Hat Gluster Storage Container Native with OpenShift Container Platform”

3.2.3. Red Hat OpenShift Container Platform Requirements

The following list provides the Red Hat OpenShift Container Platform requirements:

3.2.4. Red Hat Gluster Storage Requirements

The following list provides the details regarding the Red Hat Gluster Storage requirements:
  • Installation of Heketi packages must have valid subscriptions to Red Hat Gluster Storage Server repositories.
  • Red Hat Gluster Storage installations must adhere to the requirements outlined in the Red Hat Gluster Storage Installation Guide.
  • The versions of Red Hat Enterprise OpenShift and Red Hat Gluster Storage integrated must be compatible, according to the information in Section 3.1, “Supported Versions” section.
  • A fully-qualified domain name must be set for Red Hat Gluster Storage server node. Ensure that the correct DNS records exist, and that the fully-qualified domain name is resolvable via both forward and reverse DNS lookup.

Important

Restrictions for using Snapshot

  • After a snapshot is created, it must be accessed though the user-serviceable snapshots feature only. This can be used to copy the old versions of files into the required location.
    Reverting the volume to a snapshot state is not supported and should never be done as it might damage the consistency of the data.
  • On a volume with snapshots, volume changing operations, such as volume expansion, must not be performed.

3.2.5. Planning Guidelines

The following are the guidelines for setting up Red Hat Gluster Storage Container Native with OpenShift Container Platform.
  • Ensure that the Trusted Storage Pool is not scaled beyond 300 volumes per 3 nodes per 32GB of RAM.
  • A trusted storage pool consists of a minimum of 3 nodes/peers.
  • Distributed-Three-way replication is the only supported volume type.
  • Each physical node that needs to host a Red Hat Gluster Storage peer:
    • will need a minimum of 32GB RAM.
    • is expected to have the same disk type.
    • by default the heketidb utilises 2 GB distributed replica volume.
  • Red Hat Gluster Storage Container Native with OpenShift Container Platform supports up to 14 snapshots per volume.
  • Creation of more than 300 volumes per trusted storage pool is not supported.
  • Before running the cns-deploy tool, you must ensure that the dm_thin_pool module is loaded in the OpenShift Container Platform node. Execute the following command to verify if the dm_thin_pool module is loaded:
    # lsmod | grep dm_thin_pool
    If the dm_thin_pool module is not loaded, execute the following command to load the module:
    # modprobe dm_thin_pool