Ceph Ansible has tons of awesome capabilities, one of them is the possibility to plug on ane existing cluster that was not deployed with it. In this article, I will go through the take over procedure.

The procedure is rather simple. If the cluster was deployed with the following project there won’t be any issue:

• Ceph Deploy
• Puppet Ceph
• Chef Ceph
• Any other deployment tool that relies on ceph-disk

The procedure comes as fellow:

1. Install Ansible and add your monitors and osds hosts in it. For more detailed information you can read the Ceph Ansible Wiki
2. Set generate_fsid: false in group_vars
3. Get your current cluster fsid with ceph fsid and set cluster_fsid accordingly in group_vars
4. Run the playbook called: take-over-existing-cluster.yml like this ansible-playbook take-over-existing-cluster.yml.
5. Eventually run Ceph Ansible to validate everything by doing: ansible-playbook site.yml.

Now we can enjoy the power of Ceph Ansible :)