[AzureADDS] WIP draft of migration benefits

Author: iainfoulds

articles/active-directory-domain-services/TOC.yml

@@ -47,6 +47,8 @@
       href: synchronization.md
     - name: How password hash synchronization works
       href: ../active-directory/hybrid/how-to-connect-password-hash-synchronization.md?context=/azure/active-directory-domain-services/context/azure-ad-ds-context
+    - name: Classic deployment migration benefits
+      href: concepts-migration-benefits.md
     - name: What is Azure Active Directory?
       href: ../active-directory/fundamentals/active-directory-whatis.md?context=/azure/active-directory-domain-services/context/azure-ad-ds-context
     - name: Azure Active Directory architecture

articles/active-directory-domain-services/concepts-migration-benefits.md

@@ -0,0 +1,59 @@
+---
+title: Benefits of Classic deployment migration in Azure AD Domain Services | Microsoft Docs
+description: Learn more about the benefits of migrating a Classic deployment of Azure Active Directory Domain Services to the Resource Manager deployment model
+services: active-directory-ds
+author: iainfoulds
+manager: daveba
+
+ms.service: active-directory
+ms.subservice: domain-services
+ms.workload: identity
+ms.topic: conceptual
+ms.date: 05/20/2020
+ms.author: iainfou
+---
+
+# Benefits of migration from the Classic to Resource Manager deployment model in Azure Active Directory Domain Services
+
+Azure Active Directory Domain Services (AD DS) lets you migrate an existing managed domain that uses the Classic deployment model to the Resource Manager deployment model. Azure AD DS managed domains that use the Resource Manager deployment model provide additional features such as fine-grained password policy, audit logs, and account lockout protection.
+
+This article outlines the benefits for migration. To get started, see [Migrate Azure AD Domain Services from the Classic virtual network model to Resource Manager[howto-migrate].
+
+> [!NOTE]
+> In 2017, Azure AD Domain Services became available to host in an Azure Resource Manager network. Since then, we have been able to build a more secure service using the Azure Resource Manager's modern capabilities. Because Azure Resource Manager deployments fully replace classic deployments, Azure AD DS classic virtual network deployments will be retired on March 1, 2023.
+>
+> For more information, see the [official deprecation notice](https://azure.microsoft.com/updates/we-are-retiring-azure-ad-domain-services-classic-vnet-support-on-march-1-2023/)
+
+## Migration benefits
+
+The migration process takes an existing Azure AD DS instance that uses the Classic deployment model and moves to use the Resource Manager deployment model. When you migrate an Azure AD DS managed domain from the Classic to Resource Manager deployment model, you avoid the need to rejoin machines to the managed domain or delete the Azure AD DS instance and create one from scratch. VMs continue to be joined to the Azure AD DS managed domain at the end of the migration process.
+
+After migration, Azure AD DS provides many features that are only available for domains using Resource Manager deployment model, such as the following:
+
+* [Fine-grained password policy support][password-policy]
+* Faster synchronization speeds between Azure AD and Azure AD Domain Services
+* Two new attributes - *manager* and *employeeID*
+* Access to higher-powered domain controllers when you [upgrade the SKU][skus]
+* AD account lockout protection
+* [Email notifications alerts][email-alerts]
+* [Use Azure Workbooks and Azure monitor to view audit logs and sign-in activity][workbooks]
+* In supported regions, [Azure Availability Zones][availability-zones]
+* Integrations with other Azure products such as [Azure Files][azure-files], [HD Insights][hd-insights], and [Windows Virtual Desktop][wvd]
+* Support has access to more telemetry and can help troubleshoot more effectively
+
+Azure AD DS managed domains that use a Resource Manager deployment model help you stay up-to-date with the latest new features. New features aren't available for Azure AD DS managed domains that use the Classic deployment model.
+
+## Next steps
+
+To get started, see [Migrate Azure AD Domain Services from the Classic virtual network model to Resource Manager[howto-migrate].
+
+<!-- LINKS - INTERNAL -->
+[password-policy]: password-policy.md
+[skus]: change-sku.md
+[email-alerts]: notifications.md
+[workbooks]: use-azure-monitor-workbooks.md
+[azure-files]: ../storage/files/storage-files-identity-auth-active-directory-domain-service-enable.md
+[hd-insights]: ../hdinsight/domain-joined/apache-domain-joined-configure-using-azure-adds.md
+[wvd]: ../virtual-desktop/overview.md
+[availability-zones]: ../availability-zones/az-overview.md
+[howto-migrate]: migrate-from-classic-vnet.md