Technology

Microsoft OneLake

The single, tenant-wide data lake under Microsoft Fabric, built on ADLS Gen2, storing tables as Delta by default and exposing them through an Iceberg REST Catalog API for external engines.

6 connections3 resources1 post

Summary

What it is

The single, tenant-wide data lake under Microsoft Fabric, built on ADLS Gen2, storing tables as Delta by default and exposing them through an Iceberg REST Catalog API for external engines.

Where it fits

Microsoft's "OneDrive for data" — the shared lake every Fabric workload addresses, with open-catalog APIs (Iceberg REST + Unity Catalog Open APIs) so Snowflake, Dremio, Trino, and Databricks reach Fabric data without an export step.

Misconceptions / Traps
  • OneLake is Azure/ADLS-backed, not literally S3 — it participates in the open lakehouse via the Iceberg REST Catalog standard, not via being S3-compatible storage.
  • "Bidirectional with Snowflake" means shared Iceberg metadata over one physical copy, not two-way replication.
Key Connections
  • implements Iceberg REST Catalog Spec — IRC endpoint for external-engine access
  • enables Apache Iceberg — Fabric tables surfaced as Iceberg
  • alternative_to Amazon S3 Tables — the Azure-side managed-table-storage analogue
  • solves Vendor Lock-In — open-catalog access for Fabric-resident data

Definition

What it is

The single, tenant-wide data lake underneath Microsoft Fabric — one logical OneLake per tenant, built on Azure Data Lake Storage Gen2, that every Fabric workload (Lakehouse, Warehouse, Power BI, Real-Time Intelligence) reads and writes. Tables are stored as Delta Lake by default and exposed through an Iceberg REST Catalog (IRC) API for external engines.

Why it exists

Microsoft's answer to data-copy sprawl. Instead of each analytics product holding its own copy of the data, OneLake is a shared "OneDrive for data" that all Fabric engines address directly. The open-catalog surface (Iceberg REST + Unity Catalog Open APIs) is the interoperability bet — Fabric data should be reachable by Snowflake, Dremio, Trino, and Databricks without an export step.

Primary use cases

Tenant-wide lake for Microsoft Fabric workloads, cross-engine access to Fabric tables via the Iceberg REST Catalog API, Snowflake↔OneLake bidirectional Iceberg interop, Azure-side lakehouse storage that participates in the open table-format ecosystem.

Connections6

Outbound6
scoped_to2
Object StorageLakehouse
implements1
Iceberg REST Catalog Spec
enables1
Apache Iceberg
alternative_to1
Amazon S3 Tables
solves1
Vendor Lock-In

Resources3

BlogHigh
blog.fabric.microsoft.com/en-US/blog/how-to-access-your-micr...

Microsoft's own walkthrough of OneLake exposing Fabric tables through the Iceberg REST Catalog API for external engines.

BlogHigh
blog.fabric.microsoft.com/en-us/blog/microsoft-onelake-and-s...

GA announcement of bidirectional Snowflake↔OneLake Iceberg interoperability — read/write across both platforms over one physical copy.

DocsHigh
www.microsoft.com/en-us/microsoft-fabric/features/onelake

Official OneLake feature page covering the tenant-wide lake model and open-catalog surface.

Featured in

2026-06-10The Catalog Became the Control Plane — for Humans and Agents AlikeWithin one quarter, Apache Polaris, Unity Catalog, and Apache Gravitino all converged on the same role: the catalog is no longer where you look up where a table lives — it's where access is granted, credentials are minted, query planning happens, and AI agents are let in or kept out. The companion shift to 'the catalog is becoming a database': the catalog is also becoming the control plane.