Cassandra with TTL set up to make it completely soft state, but
this is an unusual mode of usage i.e. essentially a transient cache.
Soft state might also apply to the chat protocol within Cassandra.
New nodes can determine the state of the cluster from the chat
messages it receives and this cluster state must be constantly
refreshed to detect unresponsive nodes.
(5) In HDFS (Hadoop DFS), applications create a new file by
writing the data to it. Once the file is closed, the bytes cannot