Fly postgres is not managed postgres, it's cli sugar over a normal fly app, which the [docs](https://fly.io/docs/postgres/) make quite clear. Their docs also make clear that if you run postgres in a single-instance configuration, if the hardware it's running on has problems, you database will go down.
I believe the underlying reason that precludes failing over to a different host machine, is that fly volumes are slices of host-attached nvme drives. If the host goes down, these can't be migrated. I _think_ instances without attached volumes will fail-over to a different host.
Of course, that's not ideal, and maybe their CLI should also warn about this loudly when creating the cluster.
I believe the underlying reason that precludes failing over to a different host machine, is that fly volumes are slices of host-attached nvme drives. If the host goes down, these can't be migrated. I _think_ instances without attached volumes will fail-over to a different host.
Of course, that's not ideal, and maybe their CLI should also warn about this loudly when creating the cluster.