Does Akka Persistence provide delivery guarantees, in the meaning to guarantee that an event is actually stored in the event storage (eg Cassandra)? Otherwise, if there is no guarantee that an event was successfully persisted, this would make the whole Persistence model in Akka much less reliable and less usable as such.
If we keep persisting events of an Actor into the storage but they are not actually persisted (due to some issue) without us knowing about this, we won’t be able to recover or re-initialize the Actor properly.
Also, if persistence is not guaranteed, we won’t be confident in data that we would stream out from event storage (for example with akka-projection) for further processing. Since event storage is our focal point for events data in Akka Persistence model, missing events in there would become a major issue.