This knowledge base article addresses the limitation in Vembu Backup for Microsoft Hyper-V regarding the inability to support backups of Hyper-V virtual machines (VMs) that employ differencing disks. The issue pertains specifically to Vembu BDR Suite versions 4.0.2 and below. The article provides insights into the cause, applicable scenarios, and solutions to address this limitation.

The error occurs when attempting to back up a Hyper-V VM configured with a differencing disk using Vembu BDR Suite versions 4.0.2 and earlier.

Applicability:

This limitation is relevant under the following circumstances:

1. Utilizing Windows Server 2012 R2 or earlier versions.
2. Operating Vembu BDR Suite version 4.0.2 and below.

Note: Backing up Hyper-V VMs with differencing disks is supported on Windows Server 2016 and later versions, as well as Vembu BDR Suite version 4.1.0 and above.

To address the backup limitation for Hyper-V VMs with differencing disks, consider the following solutions:

Solution 1:

1. Upgrade the Vembu BDR Backup Server to version 4.1.0 or later. For detailed guidance, consult the Vembu Software Update Guide.

2. Upgrade the Windows Hyper-V host machine to Windows Server 2016 or a higher version.

Solution 2:

1. Merge the Differencing Disk:

   a) Open the Hyper-V Manager.

   b) Select the target VM and access the Edit Disk option in the Actions pane.

   c) Navigate to the location of the differencing disk and proceed.

   d) Choose the Merge option and select "To the parent virtual hard disk."

   e) Complete the process by clicking Finish.

After merging the disk, the backup job will either continue according to its schedule or can be manually executed by selecting the "Run now" option.

Note: This article offers solutions to address the limitation related to backing up Hyper-V VMs with differencing disks in Vembu BDR Suite versions 4.0.2 and below. Following the provided steps will enable users to mitigate the issue and optimize their backup processes.