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Chapter 1. Introduction

Red Hat OpenStack Platform director creates a cloud environment called the Overcloud. The director provides the ability to configure extra features for an Overcloud. One of these extra features includes integration with Red Hat Ceph Storage. This includes both Ceph Storage clusters created with the director or existing Ceph Storage clusters. This guide provides information for integrating Ceph Storage into your Overcloud through the director and configuration examples.

1.1. Defining Ceph Storage

Red Hat Ceph Storage is a distributed data object store designed to provide excellent performance, reliability, and scalability. Distributed object stores are the future of storage, because they accommodate unstructured data, and because clients can use modern object interfaces and legacy interfaces simultaneously. At the heart of every Ceph deployment is the Ceph Storage Cluster, which consists of two types of daemons:

Ceph OSD (Object Storage Daemon)
Ceph OSDs store data on behalf of Ceph clients. Additionally, Ceph OSDs utilize 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.


This guide only integrates Ceph Block storage and the Ceph Object Gateway (RGW). It does not include Ceph File (CephFS) storage.

1.2. Using Ceph Storage in Red Hat OpenStack Platform

Red Hat OpenStack Platform director provides two main methods for integrating Red Hat Ceph Storage into an Overcloud.

Creating an Overcloud with its own Ceph Storage Cluster
The director has the ability to create a Ceph Storage Cluster during the creation on the Overcloud. The director creates a set of Ceph Storage nodes that use the Ceph OSD to store the data. In addition, the director installs the Ceph Monitor service on the Overcloud’s Controller nodes. This means if an organization creates an Overcloud with three highly available controller nodes, the Ceph Monitor also becomes a highly available service.
Integrating a Existing Ceph Storage into an Overcloud
If you already have an existing Ceph Storage Cluster, you can integrate this during an Overcloud deployment. This means you manage and scale the cluster outside of the Overcloud configuration.

1.3. Setting Requirements

This guide acts as supplementary information for the Director Installation and Usage guide. This means the Requirements section also applies to this guide. Implement these requirements as necessary.

If using the Red Hat OpenStack Platform director to create Ceph Storage nodes, note the following requirements for these nodes:

64-bit x86 processor with support for the Intel 64 or AMD64 CPU extensions.
Memory requirements depend on the amount of storage space. Ideally, use at minimum 1 GB of memory per 1 TB of hard disk space.
Disk Space
Storage requirements depends on the amount of memory. Ideally, use at minimum 1 GB of memory per 1 TB of hard disk space.
Disk Layout

The recommended Red Hat Ceph Storage node configuration requires at least three or more disks in a layout similar to the following:

  • /dev/sda - The root disk. The director copies the main Overcloud image to the disk.
  • /dev/sdb - The journal disk. This disk divides into partitions for Ceph OSD journals. For example, /dev/sdb1, /dev/sdb2, /dev/sdb3, and onward. The journal disk is usually a solid state drive (SSD) to aid with system performance.
  • /dev/sdc and onward - The OSD disks. Use as many disks as necessary for your storage requirements.

Erase all existing partitions on the disks targeted for journaling and OSDs before deploying the Overcloud. In addition, the Ceph Storage OSDs and journal disks require GPT disk labels, which you can configure as a part of the deployment. See Section 2.10, “Formatting Ceph Storage Node Disks to GPT” for more information.

Network Interface Cards
A minimum of one 1 Gbps Network Interface Cards, although it is recommended to use at least two NICs in a production environment. Use additional network interface cards for bonded interfaces or to delegate tagged VLAN traffic. It is recommended to use a 10 Gbps interface for storage node, especially if creating an OpenStack Platform environment that serves a high volume of traffic.
Intelligent Platform Management Interface (IPMI)
Each Ceph node requires IPMI functionality on the server’s motherboard.

This guide also requires the following:


The Ceph Monitor service is installed on the Overcloud’s Controller nodes. This means you must provide adequate resources to alleviate performance issues. Ensure the Controller nodes in your environment use at least 16 GB of RAM for memory and solid-state drive (SSD) storage for the Ceph monitor data.

1.4. Defining the Scenarios

This guide uses two scenarios:

  • The first scenario creates an Overcloud with a Ceph Storage Cluster. This means the director deploys the Ceph Storage Cluster.
  • The second scenario integrates an existing Ceph Storage Cluster with an Overcloud. This means you manage the Ceph Storage Cluster separate from Overcloud management.