* CEPh (Server environment)
- Physical storage clustering
- only one access point(a mount point on one of a node) only can access one storage device
- useful
  - increase I/O performance to one of a server's I/O
  - the storage device for HA server.
  - provide single storage device(rbd) per mount point in a storage pool.
  - Not support a single storage device(rbd) to a multi-mount point ( not support multi-nodes )

* Lustre (HPC computing environment)
- http://lustre.org/
- https://downloads.hpdd.intel.com/public/lustre/
- Physical storage clustering 
- Support TCP/IP(Ethernet/IPoIB)

* GlusterFS (HPC computing environment)
- https://www.gluster.org/
- Physical storage clustering 
- Support TCP/IP, IB, Socket direct protocol