Redundancy: Complementing Modularity

This lecture delves into the concept of redundancy as a powerful technique to enhance system dependability. The instructor explains how redundancy, when combined with modularity, can be used to achieve fault tolerance, reliability, and high availability. The lecture covers the definitions of faults, errors, and failures, as well as the importance of redundancy in tolerating faults. Various forms of redundancy, such as data redundancy and processing redundancy, are discussed, along with examples like replication and geographic redundancy. The instructor also explores the use of redundancy in processing failures, fail-stop components, and fail-safe systems. Additionally, the lecture touches on the significance of leases in preventing resource leaks and the role of idempotency in ensuring reliable system recovery.