The Cost of Multitenancy

DynamoDB and ScyllaDB, both distributed NoSQL databases, share a common origin from the Dynamo paper and offer features like multi-zone and multi-region deployments, but they diverge significantly in their tenancy models. DynamoDB operates as a multi-tenant database, allowing for lower infrastructure costs and shared burst capacity among tenants, but it faces challenges like the Noisy Neighbor issue and broader impact during outages, as seen in a recent incident. In contrast, ScyllaDB employs a single-tenant architecture, providing each user with dedicated resources such as VMs, VPCs, and endpoints, which enhances isolation and limits the impact of failures to individual users. While this model offers greater resilience and workload isolation, it requires careful resource scaling and depends on EC2 for node allocation. Despite these differences, ScyllaDB optimizes performance per node to offer competitive pricing compared to DynamoDB, emphasizing stronger tenant isolation and minimizing the blast radius of potential issues.