system config

1.add sys-cluster/ceph to package.accept_keywords

  file:/etc/portage/package.accept_keywords/ceph
    sys-cluster/ceph

2. kernel config

Device Drivers --->
　　Block devices --->
　　　　Rados block device (RBD)
File systems --->
　　Network File Systems --->
　　　　Ceph distributed file system

install ceph

3. install ceph

emerge sys-cluster/ceph