Planned maintenance refers to the process of keeping the application and its surrounding ecosystem—comprising platforms, frameworks, software, the operating system, and host and guest drivers—up to date with the latest stable releases. It is important to patch software, drivers, and operating systems with the latest updates, since this helps in keeping the environment healthy from a security, performance, and future-ready perspective. Not upgrading an environment is not an option and is a fact of life. Even applications should be upgraded with enhanced functionality, bugs, and hot fixes. Every organization plans for environment and application upgrades, and typically these involve shutting down and restarting the application and operating system. It might also involve starting the physical host operating system, which, in turn, will reboot all guest VMs running on top of it. In Microsoft Azure, you can manage, get notifications and view planned maintenance windows for VMs – please refer to https://docs.microsoft.com/en-us/azure/virtual-machines/windows/maintenance-notifications for more detailed information