plan B. ✤ A plan B isn't a plan B, until is tested. ✤ Pre-heat everything before big events. ✤ Read about your IaSS in forums/email groups. ✤ Try to distribute your machines to avoid thunderbolts ;)
but finally: 1. Create a complete new environment in prod machines. 2. Deploy your code there. 3. Extract one machine from the load-balancer. 4. Create a golden-image