On ceph-client (172.16.2.101)
rbd create mystore --size 6291456 -m 172.16.2.100 -k /path/to/ceph.client.admin.keyring
modprobe rbd
rbd map mystore --pool rbd --name client.admin -m 172.16.2.100 -k /path/to/ceph.client.admin.keyring
mkfs.ext4 -m0 /dev/rbd/rbd/mystore


Then on another server:

mount -t ext4 172.16.2.101:/dev/rbd/rbd/mystore /mnt/ceph