Migrate to Amazon Keyspaces with zero downtime using ZDM Proxy

This article demonstrates how to migrate from self-managed Apache Cassandra to Amazon Keyspaces with zero downtime using the ZDM Proxy deployed on AWS Fargate with CloudFormation.

• ZDM Proxy intercepts CQL traffic at the network layer to fan out writes to both origin Cassandra and Amazon Keyspaces simultaneously
• Deploy proxy infrastructure on AWS Fargate behind a Network Load Balancer using a single CloudFormation stack
• Six migration phases: preparation, historical data loading with CQLReplicator, dual writes, validation, cutover, and decommission
• No application code changes required; proxy is transparent to CQL drivers and provides safe rollback at every stage
• Validation phase uses dual reads to compare responses between clusters and confirm discrepancy rates below 0.01%
• Security best practices include TLS termination via socat, credentials stored in AWS Secrets Manager, and least-privilege IAM roles
• Temporary costs for Fargate, NLB, and CQLReplicator offset by long-term savings from decommissioning self-managed Cassandra

The ZDM Proxy enables production-ready zero-downtime migrations to Amazon Keyspaces by maintaining data consistency across both clusters during the transition period.