How to Back Up Virtual Machines on Hyper-V While They're Running

How do I back up virtual machines on Hyper-V while they're running?

Back up your virtual machines with Langmeier Backup V-Flex — either from the Hyper-V server or inside the individual machine. Both ways are equally valid, and the machines keep running during the backup.

Windows' Shadow Copy service (VSS) makes this possible. At the moment of the backup, it creates a frozen snapshot of the data. V-Flex backs up exactly that snapshot. That's why the machines simply keep running: the backup reads the frozen state, and ongoing changes don't interfere with it.

Way 1: backing up from the Hyper-V server

Every virtual machine is contained entirely in a single file on the server. This file has the extension VHD or VHDX and contains the machine's entire drive. So if you back up this file, you back up the complete machine — including the system, programs, and data.

Here's how to set up the backup:

1. Install Langmeier Backup V-Flex on the Hyper-V server.
2. Enter the host key — it comes with your license.
3. Create a backup job that backs up the folder containing the VHD and VHDX files.

When the job starts, the Shadow Copy service creates the snapshot. V-Flex then copies the frozen disk files to the backup destination. The machines keep running in the meantime. The job is successful if it runs through without an error message and the disk files are in the destination.

Way 2: backing up inside the individual machine

Treat the virtual machine like a physical server:

1. Install Langmeier Backup directly in the machine.
2. Create a backup job there for a disk image of the system drive.
3. Choose a network drive as the backup destination — that is, a shared folder on another computer on the network.

The image is a complete copy of the entire drive, including Windows, programs, and settings. Here too, the Shadow Copy service makes sure the backup runs cleanly while the system is running. The job is successful if it ends without an error message and the image is on the network drive.

Besides the image, you can also back up individual files inside the machine: folders, documents, or databases — just like on any physical server. For example, back up your working data daily as a file backup and the entire system drive weekly as an image.

How do I restore a machine or individual files?

You restore a complete machine from the server backup in three steps:

1. Copy the backed-up VHDX file back to its place.
2. Attach the file in Hyper-V Manager to the existing machine or to a new one.
3. Start the machine.

The restore doesn't require a rescue medium.

For individual files, one step is enough:

• Pull the file directly out of the backup or out of the disk image — with no detour through the complete machine.

The stumbling block: the right administrator account

The shadow copy needs an account with administrator rights on the machine. It may not work with a domain administrator; in that case the snapshot fails, and the backup reports errors about open files.

• Enter a local administrator account in the backup job — then the shadow copy runs reliably.

Which license do I need?

A V-Flex license covers both ways. A separate host key for backing up from the server is included. For backing up inside the machine, the normal license key is enough. V-Flex works for Hyper-V, XEN, VMware, KVM, and VirtualBox.