The document discusses IBM's transition from a single-tenant Hadoop architecture to a multi-tenant Apache Spark architecture for their Watson Analytics for Social Media product. The new architecture aggregates social media data from thousands of tenants into a single stream and uses Spark, Kafka and Zookeeper to provide robust real-time analytics with low latency switching between tenants. Key aspects of the new architecture include separating analytics into tenant-specific and language-specific components, and removing state from processing components.