When using Microsoft Hyper-V Server 2012 R2 to back up Windows virtual machines with the latest integration services installed, a virtual machine checkpoint is created when the volume shadow is created. This operation adds files to the backup, including BackupSnapshot.xml and AutoRecovery.avhdx files for each disk. The checkpoint information is automatically merged as the volume shadow is completed, and does not exist for the lifetime of the backup. However, these files are available when browsing the backup data.
When you perform a restore of a full virtual machine, these files are restored along with the virtual machine. After the restore, the files are automatically integrated when the virtual machine is powered on for the first time.
You can also restore a virtual machine disk file and use that to access the disk; the files produced by the checkpoint operation are not required for that restore. If you restore a virtual machine disk and use that to create a new virtual machine, the files created for the checkpoint are not included, and the resulting virtual machine is not necessarily application-consistent with the virtual machine at the time of the backup.