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Backup of VMs on Local Storage and CSV

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Veeam Backup & Replication performs backup of Hyper-V VMs whose disks are located on the local storage and Cluster Shared Volume (CSV). In contrast to traditional backup tools that deploy an agent inside the VM guest OS and back up from within a VM, Veeam Backup & Replication uses a Veeam Data Mover Service running on the Hyper-V host or a Veeam Data Mover Service running on the off-host backup proxy. A VM is treated as an object from the perspective of the Hyper-V host — Veeam Backup & Replication captures the VM configuration and state along with VM VHD/VHDX's and creates an image-based backup of a VM.

To perform backup of Hyper-V VMs, Veeam Backup & Replication leverages the VSS framework and Hyper-V VSS components. It acts as a VSS requestor and communicates with the VSS framework. Veeam Backup & Replication obtains from VSS information about available VSS components, prescribes what components should be used, identifies volumes where files of the necessary VMs are located and triggers the VSS coordinator to create volume snapshots.

Before a snapshot of a volume is created, VMs on the volume must be prepared for the snapshot — that is, data in the VM must be in a state suitable for backup. Veeam Backup & Replication uses three methods to quiesce Hyper-V VMs on the volume: online backup, offline backup and crash-consistent backup.

Whenever possible, Hyper-V VSS uses online backup to quiesce VMs. If online backup cannot be performed, one of the other two methods is used to prepare a VM for a volume snapshot.

If online backup is not possible, Veeam Backup & Replication will fail over to the crash-consistent backup.
If you do not want to produce a crash-consistent backup, you can configure your backup jobs to use the offline backup method instead.

Backup of VMs on Local Storage and CSV Note:

Veeam Backup & Replication does not fail over to the crash-consistent backup mode if you enable application-aware processing for a job and select the Require successful processing option. In such situation, if application-aware processing fails, Veeam Backup & Replication will simply terminate the job with the Error status.