First off, why would you want a managed disk over an unmanaged one?
Greater scalability due to much higher IOPs and storage limits. There’s no longer the need to add additional storage accounts when you’re adding disk space, which has been a challenge for users that were using large virtual machines and required large storage space.
Better availability and reliability which ensures that disks are now isolated from each other in different storage scale units.
Managed disks offer an over 99.99% uptime, plus are always stored with 3 replicas of the data.
More granular access control by employing role-based access control (RBAC) security. You have granular capability to assign access to various people in your organization.
Keep reading to learn how to switch.