1. Hashed pre-splitting behavior does not work when there is only 1 shard. If you have 1 shard instead of following the default and having 2 chunks it is 0. Furthermore, if you specify numInitialChunks to be a value, the value is completely ignored and again defaults to 0 chunks. In short, the spec is not followed if there is 1 shard and it is not documented as such.