When Amanda Enterprise is configured and licensed for Hyper-V Virtual Machine backup, Amanda uses the Microsoft Windows Volume Shadow Copy Service (VSS) to back up the Hyper-V virtual machines.
To backup Hyper-V virtual machine, Zmanda Windows client will have to be installed on the Hyper-V hypervisor (Hyper-V core installation is also supported). You need a Hyper-V license for each Windows Hypervisor. The windows client installed on the hypervisor can be backup virtual machines residing on the hypervisor.
Hyper-V virtual machine backups are always Full backups. Differential or Incremental backups are not supported.
The backups are performed using the Hyper-V VSS Writer.
Hyper-V uses one of two mechanisms to back up each Virtual Machine. The default backup mechanism is called the Saved State method, where the VM is put into a saved state during the processing of the snapshot event, snapshots are taken of the appropriate volumes, and the VM is returned to previous state as part of post-snapshot event.
The other backup mechanism is called the Child VM Snapshot method, which uses the VSS writers inside the Hyper-V child virtual machine to participate in the backup. The Child VM is the virtual machine being backed up. For the Child VM Snapshot method to be used, following conditions must be met:
- Backup (Volume snapshot) Integration Service is installed and running on the child VM. The service name is Hyper-V Volume Shadow Copy Requestor.
- The child VM must be in the running state.
- The Snapshot File Location for the VM is set to be the same volume in the host operating system as the VHD files for the VM.
- All volumes in the child VM are basic disks and there are no dynamic disks.
- All disks in the child VM must use a file system that supports snapshots (for example: NTFS).
The backup mechanism is selected for each virtual machine (child VM) in Hyper-V management interface.
Requirements for Hyper-V virtual machine backup
- The Hyper-V VSS Writer must be running on the hypervisor.
- Restore of Hyper-V virtual machines and host configuration must be done to same version of Windows as the backup. For example: If the original Hyper-V backup was taken on Windows Server 2012, the restore must be done to Windows 2012 Hypervisor.
- The backup of running VM will not be performed if Child VM Snapshot method cannot be performed.
Configuring Hyper-V Virtual Machine Backups from the ZMC Backup What Page
In ZMC Backup What page, you can select Hyper-V from the Applications drop down menu. The figure below shows the Hyper-V virtual machine configuration as a backup object in the Backup set.
Host Name is the IP address or the name of Windows Hyper-V hypervisor. Click Discover button to discover all the virtual machines on the hypervisor. Zmanda Windows Client must be installed on the hypervisor to discover virtual machines.
Data Source : Users may select individual virtual machines with the Hyper-V hypervisor backup. This will backup the virtual hard disk files (.vhd or .vhdx) as well as the snapshot files (.avhd or .avhdx) of the virtual machine(s) selected. The Initial Store file is also backed up. The InitialStore.xml file, which contains the Hyper-V Authorization Store is backed up.
Encryption and Compression : Select these options as desired. They are described in more detail here.
After clicking Add button, the backup object is added to the table as shown below. You can edit the entry by clicking on the table entry.
For all Microsoft SQL Server, Microsoft Exchange, Microsoft Sharepoint, and Hyper-V backups, the name of the new machine must exactly match the name of the old machine.
Configuring Hyper-V Restores from the ZMC Restore What Page
Hyper-V virtual machines can be restored to the original Hyper-V hypervisor. The Name of hypervisor has to match the name of machine from where backup was performed (even if it is a different physical machine).
- You can only perform Express Restores. You cannot explore and restore specific virtual hard disk file(s).
- You cannot restore to original location where the virtual machine with the same name is in running state.
- The hypervisor to which restore is being performed to should have Zmanda Windows Client installed.
The actual process of restoration is identical to all other applications.