If one of the tuples anchored to a message id fails, will the other tuples process completely or they're stopped by storm?
The other tuples anchored to the same message id will continue processing as normal. Storm will fail the message id at the spout immediately, which will likely cause the spout to retry the root tuple.
The reason for this behavior is that it would be difficult/expensive to make the spout try to tell all the bolts that might be processing a tuple anchored to a failed message id that the tuple has already failed.