Fault tolerance in Smart Data Streaming

This is another comparison with Apache Kafka where Kafka replicates the messages in a distributed manner among the hosts it is running on. Which means that even if messages are lost, they are always recoverable as another host(hosts*) holds the data.

I was wondering how this happens in the case of HANA Smart Data Streaming. Are the messages stored locally on the streaming server AND in HANA as well? What happens if the streaming node is down for some reason? Are the messages lost? How is fault tolerance managed/ guaranteed in SAP Smart Data Streaming?