Microsoft Hyper-V does not provide control over pass-through disks to the host operating system. As a result, the Microsoft Software Shadow Copy provider cannot provide Agent for Hyper-V with snapshots of pass-through disks. During backup, the agent skips these disks and adds warnings to the log. You can avoid the warnings by excluding pass-through disks from the backup plan.
If you want to back up pass-through disks, install Agent for Windows or Agent for Linux in the guest operating system. An Acronis Backup & Recovery 11.5 Virtual Edition license assigned to the host enables you to install agents in an unlimited number of guest systems. For more information about how to install the agent, see the installation documentation.
After you install Agent for Windows or Agent for Linux and add the machine to the management server, the machine appears under Machines with agents in the All machines with agents group. When creating a backup plan, select the machine here rather than under Virtual machines. Or, you can connect the console to the machine directly as is done with a physical machine.
You might want to use a different backup strategy for pass-through disks. For example, if these disks contain frequently changing databases, you can back them up more often than the operating system, or use different settings for them. In this case, create a separate backup plan for these disks.