Filesystem COW support

Subject:

ZFS and Ceph filesystems use Copy on Write(COW)

Details:

ZFS is an option when creating a Storage Pool on QuantaStor deployments.
The QuantaStor Scale-out Block feature uses a different filesystem solution based on Ceph.

Both the ZFS and Ceph filesystems use `Copy on Write` to support instant snapshotting and replication features.

Additional detail can be found here:

ZFS:
http://www.oracle.com/technetwork/server-storage/solaris11/documentation/oraclesolariszfsstoragemanagement-360232.pdf

Ceph:
http://docs.ceph.com/docs/master/