Veeam Backup and Replication provides two different backup modes to process Hyper-V backups, both relying on the Microsoft VSS framework.
- On-Host backup mode, for which backup data processing is on the Hyper-V node hosting the VM, leveraging non transportable shadow copies by using software VSS provider.
- Off-Host backup mode, for which backup data processing is offloaded to another non clustered participating Hyper-V node, leveraging transportable shadow copies using Hardware VSS provider provided by the SAN storage vendor.
Backup mode availability is heavily dependant on the underlying virtualization infrastructure, leaving Off-Host backup mode preferred to protect virtual machines hosted on SAN storage volumes or SMB3 shares.
Performance wise, since both backup modes are using the exact same Veeam transport services, the only differentiating factors will be the additional time requested to manage transportable snapshots (in favor of On-Host mode) and the balance between compute and backup resources consumption during backup windows (in favor of Off-Host mode).
We recommend to use On-Host backup proxies unless there are dire reasons to not use them. The pros of On-Host proxies do outweigh the cons a lot.
Every Hyper-V server added to Veeam Backup & Replication will be installed with the Veeam On-Host proxy role automatically.
|On-Host||Simplified management||Requires additional resources from hypervisors during backup window for IO processing and optimization|
|No 3rd party hardware VSS provider|
|No additional hardware required|
|Use with any Hyper-V infrastructure|
|Scales with the infrastructure|
|Off-Host||No impact on production Hyper-Vs||3rd party hardware VSS provider dependency|
|Additional delay for snapshot transportation|
|Only available for (some) SAN storage or SMB3 shares|
The OS is defined by your Hyper-V infrastructure. For On-Host implicitely and for Off-Host explicitely as you need to run the same Hyper-V version on the Off-Host proxy as on the protected infrastructure.
Proxy sizing works as for vSphere Proxies - please refer to that section.