14 Backup / Restore Microsoft Virtual Machines

This section describes in detail how to backup and restore virtual machine running on Microsoft Hyper-V Server with OBM.

Table of contents

Please ensure that the following requirements are met by the Hyper-V server:

OBM version 6.13 or above is installed on the Hyper-V server.
The Hyper-V management tools are installed on the Hyper-V server.
Consider increasing the JVM (Java Virtual Machine) memory allocation to improve performance of the backup operation.
It is recommended that the temporary directory have disk space of at least 50% of the largest sized virtual machine to be backed up.
For backup of virtual machine with snapshot, backup of the whole VM instead of individual disk is highly recommended.
The current virtual hard disk (VHD) specification limits the size of a virtual hard disk to be 2040 GB (2 TB), which can fit a volume of size 2040 GB minus 2 MB.

For details, please refer to:
http://blogs.technet.com/b/ranjanajain/archive/2010/03/23/virtual-hard-disk-vhd-architecture-explained.aspx
http://technet.microsoft.com/en-us/library/dd183729%28v=ws.10%29.aspx

The following are limitations of the MS VM backup module:

Virtual machine backed up with the MS VM backup module can be restored to the Hyper-V server with the same version.
Backup of virtual machine with pass through disk (directly attached physical disk) is not supported.
The virtual machine cannot start up if the guest operating system virtual disk is not restored.
Restore of individual virtual disk to a different virtual machine is only supported for virtual disk with no snapshot.
For backup of individual virtual disk, the restored virtual machine does not support the reversion of previous snapshots, if the snapshot contains disks which are not previously backed up by OBM.

The following steps are performed during a backup job:

Connection from the backup client to the backup server is established.
Download the server file list from the backup server.
Commands are issued to the hypervisor to create snapshot (memory dump) of the virtual machine with Volume Shadow Copy.

Important:
The corresponding virtual machine will be paused during the snapshot process, and resume when the snapshot is completed.

Do not attempt to start the virtual machine while it is in the saving state. The snapshot created may be invalid.

Furthermore, the corresponding virtual machine uptime will also be reset to 00:00:00 in the Hyper-V Manager.
After generating all files, the files are copied to the temporary spool path and upload to OBS.
Commands are issued to the hypervisor to remove the Volume Shadow Copy snapshot created.
Backup completed successfully.

Refer to the following instructions to backup VM running on Microsoft Hyper-V Server:

Select the [Backup Settings] button and the button to start the New Backup Set Wizard.
Create a MS VM Backup set by selecting [MS VM Backup] from the backup set type dropdown menu.

Alternatively, select individual virtual disk for backup by expanding the corresponding VM sub tree.

Note:
For backup of individual virtual disk, configuration files of the VM are also backed up.

Important:
For backup of virtual machine with snapshot, backup of the whole VM is highly recommended (instead of selective virtual disk).

Note:
Multiple backup schedules of different types can be configured for the same backup set.