Resizing Pool to 1 has been disabled by default on Ceph Pacific stable 6.0

Question

I implemented Ceph Pacific Stable 6.0 with Ceph-Ansible on Ubuntu 20.04 LTS but when I want to change size of my pool from 3 to 1 with following command:

sudo ceph -n client.admin --keyring=/etc/ceph/ceph.client.admin.keyring osd pool set cephfs_data size 1

I get following error:

Error EPERM: configuring pool size as 1 is disabled by default.

Answer 1

1. Add the following option under section [global] in ceph.conf:

mon_allow_pool_size_one = true

2. Restart the monitor service