Survive the failures

The notes service is live, and the ops team wrote down what happened this year. Design the system so that all four scenarios pass: (1) on a normal day a user saves a note and reads it back; (2) the machine running one app server dies; (3) the machine running the database dies, and no notes may be lost; (4) on Monday morning traffic is five times the usual, more than one server can handle. Fill the slots. Run test plays every scenario against your design and shows where it breaks.