[...]
I want to learn ceph, and i am really having no knowledge on ceph.
I decided to follow the official doc on
ceph.com site.
It is said to use ceph-deploy which is not working.
You could do like I did;
start gathering some Ceph know-how by targeting 3 x86_64 VMs running Fedora29, CentOS7 or
RHEL7.
Once you are comfortable using ceph-ansible against these, try again with your
raspberry3B+ machines.
pcfe