Step-by-Step Guide: Deploy a Ceph Storage Cluster on CentOS 7 with Ansible

Deploy Ceph Cluster

Three machines running CentOS 7.9 are prepared; the following steps must be executed on each node.

Configure hosts resolution

cat >> /etc/hosts <<EOF
192.168.2.23 node1
192.168.2.24 node2
192.168.2.25 node3
EOF

Disable firewall and SELinux

systemctl stop firewalld && systemctl disable firewalld
setenforce 0 && sed -i 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/selinux/config

Set hostnames on each node

hostnamectl set-hostname node1
hostnamectl set-hostname node2
hostnamectl set-hostname node3

Configure time synchronization

systemctl restart chronyd.service && systemctl enable chronyd.service

Set up password‑less SSH

ssh-keygen
ssh-copy-id -i .ssh/id_rsa.pub node1
ssh-copy-id -i .ssh/id_rsa.pub node2
ssh-copy-id -i .ssh/id_rsa.pub node3

Install pip, Ansible and Git

yum install python-pip ansible git -y

Deploy Ceph Cluster

Clone the repository

git clone https://github.com/ceph/ceph-ansible.git
cd ceph-ansible
git checkout stable-4.0

Install Ansible dependencies

pip install --upgrade pip
pip install -r requirements.txt

Update Ansible hosts file

cat >> /etc/ansible/hosts <<EOF
[mons]
node1
node2
node3

[osds]
node1
node2
node3

[mgrs]
node1

[mdss]
node1
node2
node3

[clients]
node1
node2
node3

[rgws]
node1
node2
node3

[grafana-server]
node1
EOF

Backup group_vars YAML files

cd ceph-ansible/group_vars
for file in *; do cp $file ${file%.*}; done

Modify group_vars/all.yml

---
dummy:
  mon_group_name: mons
  osd_group_name: osds
  rgw_group_name: rgws
  mds_group_name: mdss
  client_group_name: clients
  mgr_group_name: mgrs
  grafana_server_group_name: grafana-server
  configure_firewall: False
  ceph_origin: repository
  ceph_repository: community
  ceph_mirror: //mirrors.aliyun.com/ceph
  ceph_stable_key: //mirrors.aliyun.com/ceph/keys/release.asc
  ceph_stable_release: nautilus
  ceph_stable_repo: "{{ ceph_mirror }}/rpm-{{ ceph_stable_release }}"
  public_network: "192.168.2.0/24"
  cluster_network: "192.168.2.0/24"
  monitor_interface: ens33
  osd_auto_discovery: true
  osd_objectstore: filestore
  radosgw_interface: ens33
  dashboard_admin_password: asd123456
  grafana_admin_password: admin
  pg_autoscale_mode: True

Modify group_vars/osds.yml

devices:
  - /dev/sdb

Edit site.yml (illustrated below)

Start installation

ansible-playbook -i /etc/ansible/hosts site.yml

The process finishes in about ten minutes.

After installation, a warning appears because pg_autoscale_mode was set to False in all.yml. Enable it manually:

ceph osd pool set <pool-name> pg_autoscale_mode on

Result screenshots: