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Hyper-V virtual machines

This section provides considerations and requirements for protecting Hyper-V environments.

Preparing for Hyper-V backups

Following is a summary of the high-level steps used to back up Hyper-V virtual machines. Included are links to detailed instructions for each procedure.

1 Review Hyper-V virtual machines.
2 Install the Unitrends Windows agent on your Hyper-V host. See Installing the Windows agent.
3 Add the Hyper-V host to your Unitrends appliance. See Adding a virtual host.
4 Create backup jobs for your VMs. See Creating backup jobs.

Best practices and requirements for Hyper-V protection

Review the information in these topics before implementing Hyper-V host-level protection:

Hyper-V best practices
General Hyper-V requirements
Additional Hyper-V requirements

Hyper-V best practices

Follow these recommendations:

Adhere to Microsoft’s best practices for virtualization. For a list of Microsoft documents on virtualization, see Microsoft Virtualization: Hyper-V best practices.
Install the latest Windows agent on your Hyper-V host for best performance.
To protect the file system and operating system of the Hyper-V host, you must run asset-level backups. For details, see Asset-level Backups Overview. Any files belonging to the Hyper-V application are automatically excluded from asset-level backups of the Hyper-V host.
After making any configuration changes to a VM in the Hyper-V manager, such as creating or deleting a snapshot, adding a new disk, or converting a disk from VHD to VHDX format, you must run a new full backup to ensure the integrity of the VM’s backup groups. After running a new full back up, you can continue protecting the VM with its existing schedule.
A cluster with a single cluster shared volume does not follow Microsoft’s best practices and may be unreliable. If you have VMs in a cluster with a single CSV, protect them as you would physical machines, by using asset-level backups.
In some cases, you may want or need to protect VMs using asset-level backups. For recommendations, see Protecting Hyper-V virtual machines at the asset level.
Do not run host-level backups for VMs that you are protecting at the guest OS level. Doing so can compromise log truncation changes for applications and lead to other undesirable results.
If recovery time objectives are very important, set up Hyper-V instant recovery to quickly to spin up a failed VM from host-level backups.

General Hyper-V requirements

The following requirements must be met for host-level protection of Hyper-V virtual machines.

Item

Description

Hyper-V host

The following are required for the Hyper-V host:

The Hyper-V host must be a supported version listed in the Unitrends Compatibility and Interoperability Matrix.
The Unitrends Windows agent must be installed on the host as described in Installing the Windows agent. (It is not necessary to install agents on your virtual machines.)
For cluster configurations, be sure to install the same agent version on all hosts in the cluster.

Microsoft VSS

Microsoft’s Volume Shadow Copy Service (VSS) and the Hyper-V VSS writer must be installed and running on the Hyper-V host.

Integration Services

To avoid VM downtime, Unitrends recommends online backups. To perform online backups, you must install Integration Services in the guest operating system to enable the VM to create a child state snapshot. The host then uses this snapshot to perform an online backup of the virtual machine.

For online backups, the following conditions must be met on the protected VMs:

The latest version of backup Integration Services must be installed and enabled. For a list of guest operating systems for which Integration Services is supported, see the Microsoft document Hyper-V Overview.
The VM’s VHD/VHDX files and snapshot file location must be set to the same volume in the host operating system.
All volumes must reside on basic disks and the VMs cannot have dynamic disks.
All disks must use a file system that supports snapshots (for example, NTFS).

If an online backup cannot be performed, the VM is temporarily put in a saved state. In saved state there is a brief downtime during the backup.

Virtual machine configuration

VMs must adhere to the following:

Generation 1 and 2 VMs are supported. Generation 2 VMs require Windows Server Hyper-V 2012 R2 as the recovery target.
The Hyper-V VM cannot be configured with pass-through disks. To protect a VM with pass-through disks, use asset-level protection instead.

Additional Hyper-V requirements

These additional requirements may apply to your environment.

Item

Description

Virtualized Active Directory servers

To ensure database consistency, you must set up the virtualized Active Directory (AD) server in accordance with Microsoft best practices. If all Microsoft considerations are not addressed, backup and restore of the virtual machine may yield undesired results. If you prefer not to research these best practices, it is recommended to install the agent on the VM and protect it as you would a physical server (leveraging Microsoft’s VSS writers).

Distributed File System environments

Distributed File System (DFS) Namespaces and DFS Replication offer high-available access to geographically dispersed files. Because of the replication and syncing operations in DFS environments, you must set up the virtual machine in accordance with Microsoft best practices to ensure database consistency. If all Microsoft considerations are not addressed, backup and restore of the virtual machine may yield undesired results. If you prefer not to research these best practices, it is recommended to install the agent on the VM and protect it as you would a physical server (leveraging Microsoft’s VSS writers).

Storage on SMB 3.0 shares

Unitrends can protect virtual machines with disk storage located on SMB 3.0 shares. When these VMs are backed up, the Hyper-V agent creates a VSS snapshot on the remote server and exposes it to the Hyper-V host through the SMB share pathing. The agent then backs up the VM’s files from the remote snapshot location. When the backup completes, all VSS snapshots created for the backup are removed from the server hosting the SMB share.

The following are required to protect Hyper-V VMs with SMB 3.0 file storage:

The File Server and the File Server VSS Agent Service roles must be installed on the server hosting the SMB 3.0 shares. For instructions on installing these roles, see KB 1776.
The Unitrends Hyper-V agent installed on the Hyper-V host must be granted read/write access to remote SMB 3.0 shares.

The most secure option to provide all necessary access is to change the login account for the Unitrends Hyper-V agent service from "bpagent" to the domain administrator account.

If permissions for the domain administrator do not allow access to all files for file-level backups of the Hyper-V host, run the agent as a local system account on the Hyper-V host and grant it read/write permission for the SMB shares. For instructions, see KB 1777.

The servers hosting the VMs and SMB shares must belong to the same Windows domain.
The VM can contain one or more disks on SMB 3.0 shares. Disks can reside on the same share or different shares hosted by one or more servers in the same domain. All servers participating in the VM backup must belong to the same domain.
Faster incrementals on 2012 and 2012 R2

Unitrends leverages a Hyper-V changed-block-tracking (CBT) driver that greatly increases incremental backup performance on 2012/2012 R2 hosts.

To use this driver, simply install Windows agent version 8.1.0-3 or higher on your Hyper-V hosts. The CBT driver is automatically installed with the Windows agent.

To verify that the the CBT driver was used, view backup details and look for the following in the Output: CBT DRIVER ACTION IS ENABLED. If the driver has been uninstalled or corrupted, backups complete with a warning to indicate that the CBT driver was not used.

Windows agent push

To use the push feature to install the Windows agent and agent updates on the Hyper-V host, see Installing the Windows agent for additional requirements.