Redundancy and Randomization as Effective Tools for Improving Performance

Redundancy is widely used for fault tolerance: storing multiple copies of data, executing the same instructions on multiple processors, providing alternate paths in a communication network, etc. However, redundancy can also be used for improving performance and even cost-performance. In some cases, combining it with randomization is highly beneficial: randomization makes performance insensitive to specific scenarios (e.g., balances average load), and redundancy is used to handle the rare “bad” cases. Moreover, this approach often results in the ideal combination of “selfish” policies with “good citizenship”. We illustrate this using examples from our own past research, and offer important insights. The ideas are applicable to numerous fields.