You have an Azure virtual machine named VM1 that runs Windows Server and has the following configurations: Size: D2s_v4 Operating system disk…

Changing the size of an Azure virtual machine (VM) requires a restart. When you resize a VM, Azure may need to move it to a different physical host or cluster that has the resources available for the new size. This process involves stopping the VM on the current host, re-provisioning it with the new size on a new host, and then starting it again. This sequence of events constitutes downtime for the virtual machine. In contrast, both attaching a new data disk and detaching an existing one are "hot" operations that can be performed on a running Windows Server VM without requiring a reboot.

A. Detaching the data disk only and adding a new standard SSD.

These are both online operations. Azure supports hot-adding and hot-detaching data disks for running Windows VMs, so no downtime is required for these actions.

B. Detaching the data disk only.

Detaching a data disk from a running Windows VM is a supported online operation and does not necessitate downtime.

D. Adding a new standard SSD only.

Adding (attaching) a new data disk to a running Windows VM is a supported "hot-add" operation and does not require downtime.

1. Microsoft Learn. (2023). Resize a virtual machine. Azure Virtual Machines documentation. Retrieved from https://learn.microsoft.com/en-us/azure/virtual-machines/resize-vm.

Reference Section: Resize a VM. The document states

"If the VM is currently running

changing its size will cause it to be restarted." This explicitly confirms that resizing requires downtime.

2. Microsoft Learn. (2023). Detach a data disk from a Windows virtual machine. Azure Virtual Machines documentation. Retrieved from https://learn.microsoft.com/en-us/azure/virtual-machines/windows/detach-disk.

Reference Section: Detach a data disk using the portal. The first paragraph states

"You can detach a data disk from a Windows virtual machine while it's running." This confirms detaching a disk is an online operation.

3. Microsoft Learn. (2023). Attach a managed disk to a Windows VM. Azure Virtual Machines documentation. Retrieved from https://learn.microsoft.com/en-us/azure/virtual-machines/windows/attach-managed-disk-portal.

Reference Section: Find

attach

and initialize a new data disk. The procedure described does not require the VM to be stopped

confirming that attaching a disk is a "hot-add" or online operation.