Legacy Warehouses to Open Lakehouses: A Step-by-Step Migration Playbook

This article provides a comprehensive migration playbook for transitioning from legacy proprietary data warehouses to open lakehouses using Iceberg and Dremio. It covers five phases: inventorying existing assets, designing a medallion architecture (bronze/silver/gold layers), running a lighthouse migration, migrating in waves, and optimizing governance. The key insight is that the technical migration is solvable, but building stakeholder trust is harder. It addresses BI tool compatibility, incremental loads, streaming sources, and common failure modes. The article is highly relevant to IT/technology, focusing on data engineering, cloud architecture, and modern data stack best practices.