Altaro Software's Hyper-V Backup is fully Hyper-V aware and offers a number of advanced features including:
- VSS support for zero downtime backups, including VSS application-aware backups for Exchange and SQL VMs;
- Scheduling of backups for cluster shared volumes (CSV);
- Reverse delta backups with reduplication;
- Flexible backup scheduling;
- InstantBoot for booting a VM directly from backup;
- File-level restores; and
- Live backup of Linux VMs running in Hyper-V.
Besides their commercial edition, which starts at $345 per host, they offer a free edition that allows you to backup two VMs.