Chapter 1. Integrating an overcloud with Ceph Storage

Red Hat OpenStack Platform director creates a cloud environment called the overcloud. You can use director to configure extra features for an overcloud, such as integration with Red Hat Ceph Storage. You can integrate your overcloud with Ceph Storage clusters created with director or with existing Ceph Storage clusters.

This guide includes instructions about how to integrate an existing Ceph Storage cluster with an overcloud. This means that director configures the overcloud to use the Ceph Storage cluster for storage needs. You manage and scale the cluster itself outside of the overcloud configuration.

1.1. About Ceph Storage

Red Hat Ceph Storage is a distributed data object store that provides performance, reliability, and scalability. Distributed object stores accommodate unstructured data, and clients can use modern object interfaces and legacy interfaces simultaneously. At the core of every Ceph deployment is the Ceph Storage cluster, which consists of several types of daemons. The following are the primarily two types of daemons:

Ceph OSD (Object Storage Daemon)
Ceph OSDs store data on behalf of Ceph clients. Additionally, Ceph OSDs use the CPU and memory of Ceph nodes to perform data replication, rebalancing, recovery, monitoring and reporting functions.
Ceph Monitor
A Ceph monitor maintains a master copy of the Ceph storage cluster map with the current state of the storage cluster.

For more information about Red Hat Ceph Storage, see the Red Hat Ceph Storage Architecture Guide.

1.2. Deploy the Shared File Systems service with external CephFS

Red Hat OpenStack Platform director can deploy the Shared File Systems service (manila) with CephFS. CephFS can be consumed either through the native CephFS protocol or through the NFS protocol.

For more information about these storage protocols, see Ceph File System architecture in CephFS Back End Guide for the Shared Files Systems Service.

Important

You cannot use the Shared File Systems service (manila) with the CephFS native driver to serve shares to Red Hat OpenShift Container Platform through Manila CSI. Red Hat does not support this type of deployment. For more information, contact Red Hat Support.

Important

The Shared File Systems service (manila) with CephFS through NFS fully supports serving shares to Red Hat OpenShift Container Platform through Manila CSI. This solution is not intended for large scale deployments. For important recommendations, see https://access.redhat.com/articles/6667651.

Important

To use native CephFS shared file systems, clients require access to the Ceph public network. When you integrate an overcloud with an existing Ceph cluster, director does not create an isolated Storage network to designate as the Ceph public network. This network is assumed to already exist. Do not provide direct access to the Ceph public network, instead, allow tenants to create a router to connect to the Ceph public network.

For more information about security considerations, see Native CephFS back-end security in the Deploying the Shared File Systems Service with native CephFS guide.

When you use CephFS through the NFS protocol, director deploys the NFS-Ganesha gateway on Controller nodes managed by Pacemaker (PCS). PCS manages cluster availability by using an active-passive configuration.

Note

This feature is supported with Ceph Storage 4.1 or later in the Ceph 4 cycle or Ceph Storage 5.0 or later in the Ceph 5 cycle. You must install the latest version of the ceph-ansible package on the undercloud. For more information about how to determine the Ceph Storage release installed on your system, see Red Hat Ceph Storage releases and corresponding Ceph package versions.

For more information about how to update the ceph-ansible package on the undercloud, see Section 3.1, “Installing the ceph-ansible package”.

Prerequisites

The following prerequisites are required to configure the Shared File Systems service with an external Ceph Storage cluster:

For more information about Red Hat Ceph Storage, see the Red Hat Ceph Storage File System Guide.

1.3. Configure Ceph Object Store to use external Ceph Object Gateway

Red Hat OpenStack Platform (RHOSP) director supports configuring an external Ceph Object Gateway (RGW) as an Object Store service. To authenticate with the external RGW service, you must configure RGW to verify users and their roles in the Identity service (keystone).

For more information about how to configure an external Ceph Object Gateway, see Configuring the Ceph Object Gateway to use Keystone authentication in the Using Keystone with the Ceph Object Gateway Guide.