Hyper-V Backup and Restore

Backup for Windows features backup and restore of Hyper-V virtual machines.

This chapter covers the following topics:

What Is Hyper-V

Hyper-V is Microsoft's hardware virtualization product. Hyper-V allows to create and run a software version of a computer, called a virtual machine. Each virtual machine acts like a computer running an operating system and programs.

Hyper-V runs each virtual machine in its own space, which allows running more than one virtual machine on the same hardware at the same time.

What Is a Hyper-V Checkpoint

A Hyper-V checkpoint is a restore point of a virtual machine. Hyper-V checkpoints allow to keep existing states of virtual machines, so in case of any crash, it is easy to roll a virtual machine back to a previous state.

Windows 10 Hyper-V environment is enriched with two types of checkpoints:

  • Standard checkpoints
  • Production checkpoints.

Standard Hyper-V Checkpoint

A standard checkpoint contains a snapshot of a Hyper-v virtual machine, its memory state, but does not contain a complete copy of VM data.

Production Hyper-V Checkpoint

A production checkpoint is a consistent state of a Hyper-V machine. A snapshot of the virtual machine memory state is not taken when using a production checkpoint.

Production checkpoints do not include information about running applications, while standard checkpoints contain the current state of current applications

To learn more about Hyper-V checkpoints, refer to the Work with Checkpoints chapter at docs.microsoft.com

Checkpoint Creation Logic in MSP360 (CloudBerry) Backup

Checkpoint creation logic depends on Hyper-V configuration. The following cases are possible:

  • Production checkpoints are selected.
  • Standard checkpoints are selected
  • Checkpoints are disabled (no checkpoint type selected)

MSP360 (CloudBerry) Backup always starts by trying to create a checkpoint of the selected type first. In the event of a failure, a recovery inconsistent checkpoint will be created. Recovery inconsistent checkpoint does not contain VM VSS snapshot. If no checkpoint type is set, MSP360 (CloudBerry) Backup starts by trying to create a recovery consistent checkpoint using VM VSS snapshot. In the event of a failure, a recovery inconsistent checkpoint will be created. Recovery inconsistent checkpoint does not contain VM VSS snapshot. In case of the recovery consistent checkpoint usage, I/O activities that are quiesced at a point of creating VM VSS shapshot will be resumed to ensure successful restore. In case of a recovery inconsistent checkpoint is used for restore, the restore may fail.

Hyper-V Machine Backup

The new Hyper-V backup approach uses WMI API for backups instead of a VSS Writer mechanism.

The basics of Hyper-V backup consist of the following steps:

  • Once a Hyper-V backup plan is run, a Hyper-V host is accessed
  • New checkpoints are created for virtual machines specified in a backup plan. Virtual machines are always backed up sequentially. The new checkpoint is created while a virtual machine is being processed
  • Once checkpoints are read, they are uploaded to backup storage along with required VM configurations
  • As the checkpoint is uploaded to backup storage, it is deleted on a Hyper-V host side.

Pass-Through Disks

Currently, virtual machines with pass-through disks are not backed up. If such a virtual machine is included in the backup plan, only recovery snapshots are backed up.

As a workaround, you can install another Backup for Windows instance on a virtual machine with pass-through disks and create an image-based backup plan for this VM.

Note that the new Backup for Windows instance requires a separate license