I'm using a rpm build directly from ceph, ceph-osd-16.2.1-0.el8.x86_64 I tweaked the configuration with a custom cluster name and custom installation dir In the unit, there is the configuration: ExecStartPre=/usr/libexec/ceph/ceph-osd-prestart.sh --cluster ${CLUSTER} --id %i And this script check the osd path with an hard coded value: data="/var/lib/ceph/osd/${cluster:-ceph}-$id" It doesn't use the key from the configuration file. But using ceph-conf would have solve the problem: $ CEPH_CONF=/data/ceph/conf/ngceph.conf CLUSTER=ngceph ceph-conf --name osd.1 --show-config-value osd_data /data/ceph/data/osd/ceph.1