Each Microsoft Fabric tenant's single logical data lake, built on ADLS Gen2. Every Fabric workload stores and reads its data there without moving or duplicating it.
In DP-900: OneLake shortcuts provide zero-copy access to ADLS, Amazon S3, or Google Cloud Storage data; mirroring continuously replicates databases such as Azure SQL Database or Cosmos DB into OneLake.
OneLake is a concept that can show up on the exam. Check the full guide to see it in context.