Does SENTRY_TSDB require a good reliability for its stored data?

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Hi,

I am trying to understand the reliability of various sentry components.
From docs it is mentioned that a Time-series Storage, with "RedisSnuba" implementation, is used to "display aggregate information for events and projects, as well as calculating (in real-time) the rates of events.".

1. Since it uses Redis, do I need to backup those data?
2. What happens if Redis loses relevant data? Will Sentry to be able to rebuild what is needed to function?
3. If no SENTRY_TSDB_OPTION is specified, I assume it uses the global redis instance across other components. Is that true?
4. For high volume sentry cluster, is it recommended to use a separated redis cluster for TSDB?