Choosing VSS Provider (Microsoft Hyper-V Server 2012 R2 and Earlier)

Before you configure backup jobs, it is recommended that you decide what VSS provider will be used to create and maintain volume shadow copies.

By default, Veeam Backup & Replication automatically selects a VSS provider on every volume. Every 4 hours, it rescans all Microsoft Hyper‑V hosts added to the backup infrastructure and updates information about connected volumes. Veeam Backup & Replication also collects information about software and hardware VSS providers available on every volume.

If hardware providers are available, Veeam Backup & Replication selects a hardware provider to create volume shadow copies on a volume. If no hardware providers are installed, Veeam Backup & Replication selects the VSS system software provider. However, you can manually assign a VSS provider on every volume if necessary.

If both software and hardware providers are available for a volume, it is recommended that you select a hardware provider. Although software providers are generally applicable to a wider range of storage platforms, they have a number of limitations:

Software providers do not support transportable volume shadow copies and cannot be used for off-host backup.
By default, jobs working with the same volume can take up to 4 snapshots of a volume simultaneously. If necessary, the number of snapshots can be increased.
Hardware providers operate at the storage system controller level. Software providers operate at the software level, between the file system and the volume manager, and can cause a significant performance overhead on the source host.