Design a robust orchestration strategy for a distributed system consisting of five independent microservices (Order, Inventory, Payment, Shipping, Notification) using the Choreography-based Saga pattern. Your response must address: 1) How to maintain data consistency across services without distributed transactions (2PC). 2) A mechanism to handle compensating transactions in case of failure during the Shipping phase. 3) A detailed diagram or textual description of the event flow, specifically focusing on the correlation of events and state management. 4) Strategies to prevent race conditions when high-volume concurrent orders attempt to reserve the same inventory item.