In the context of log aggregation, Kafka and Redis are two prominent tools, each with distinct functionalities and performance characteristics. Kafka, designed as a distributed, partitioned, and replicated commit log service, excels in handling large volumes of data with its disk-based storage, offering scalability and fault tolerance through parallelism and replication. It supports log aggregation by allowing logs to be fed into various topics, which are then processed by consumers. In contrast, Redis operates as an in-memory data store, ideal for real-time data processing and scenarios requiring minimal latency but less suited for long-term data retention due to its limited memory capacity. Performance tests highlight Kafka's ability to handle high throughput, especially in asynchronous replication settings, while Redis benefits from pipelining, allowing multiple requests without waiting for replies. Both tools, when integrated with solutions like Fluentd, can enhance systems like Elasticsearch by protecting data streams and enabling robust log management. While Redis is suitable for short-lived message processing, Kafka is preferable when dealing with large data volumes that need retention.