The transition to Microsoft Defender XDR introduces significant governance changes that are crucial for a unified Security Operations Center to function effectively. Initially, existing Azure RBAC assignments remain functional, and Sentinel data stays in its current location, ensuring day-one continuity. However, the platform enables powerful new capabilities, including data-scoped permissions not tied to a single workspace. It also introduces a tiered data model, allowing for long-term data retention at a lower cost and multi-tenant management spanning up to 100 customer tenants with a single sign-in.The shift involves evolving roles and personas, moving from classic Azure RBAC to Unified RBAC (URBAC). While URBAC becomes the primary source of permissions once enabled, Azure RBAC continues to function for specific use cases like automation roles and service principals, which are not yet fully supported by URBAC. URBAC offers a more granular approach, with data-scoped and cross-workspace permissions, and supports row-level RBAC for enhanced security. Security analysts, engineers, and managers will see changes in how their permissions are managed within this new model.A key governance construct is the Sentinel data lake, which mirrors analytics-tier data, providing a single source of truth for historical threat hunting, compliance, and investigations. This separation of "hot" detection data from "warm/cold" investigation data optimizes costs and simplifies querying. The data lake supports KQL queries across all connected Sentinel workspaces and can query external data sources without moving them.For Managed Security Service Providers (MSSPs) and large enterprises, multi-tenant management in Defender XDR simplifies operations by offering a unified cross-tenant view. While it does not replace Azure Lighthouse, it streamlines daily tasks with a centralized management system for up to 100 tenants. This unified view enhances incident investigation, advanced hunting, and content distribution across multiple environments. The transition emphasizes a move towards a more integrated and capable governance framework for modern security operations.