Azure Active Directory Domain Services (AD DS) now supports Azure managed disks. Azure managed disks provide a greater degree of availability and resilience to failures. This enables the domain controllers of your managed domain to be more resilient to storage-related outages.
All newly created managed domains now use Azure managed disks by default. Existing managed domains will slowly be migrated to use Azure managed disks over the course of calendar year 2018.
Read about the benefits of Azure managed disks in the documentation.