root@yster4:~# ceph-volume lvm prepare --bluestore --data /dev/sda --block.db /dev/sdc4
Running command: /usr/bin/ceph-authtool --gen-print-key
Running command: /usr/bin/ceph --cluster ceph --name client.bootstrap-osd --keyring /var/lib/ceph/bootstrap-osd/ceph.keyring -i - osd new 6987a371-1b96-4646-b77a-bd800aa388eb
Running command: vgcreate --force --yes ceph-3578bb74-3136-4004-81ac-0dfddb0caaf8 /dev/sda
 stderr: Device /dev/sda not found (or ignored by filtering).
--> Was unable to complete a new OSD, will rollback changes
--> OSD will be fully purged from the cluster, because the ID was generated
Running command: ceph osd purge osd.0 --yes-i-really-mean-it
 stderr: purged osd.0
-->  RuntimeError: command returned non-zero exit status: 5