You need at least 1 backup and/or replica. Availability is kinda good: You could lose one/few tenants but that not take down all the rest (if they are isolated

You need at least 1 backup and/or replica. Availability is kinda good: You could lose one/few tenants but that not take down all the rest (if they are isolated properly). Is MUCH worse if all the db made the fancy way get down, or worse, you get a cascade of latency and/or crashed by the interlinked nature of the "scalable architecture that is fact share-everything global singleton". And you can get a bit fancy (not done it myself, my customers tolerate a bit of downtime) of fork the tenant and upload it another node.