We've got several customers that either run Veeam 100% virtually on separate backup storage or that use a physical backup server (think HPE Apollo) with ESXi on it for a Veeam VM and an HPE StoreOnce VSA appliance for long-term GFS retention. Using a cheaper SAN for backup storage you can even build lovely HA Veeam clusters.
Such environments have one downside though when using block storage as a source: you need messy workarounds for storage snapshotting to function. For iSCSI you would have to use an in-guest iSCSI initiator and for FC you would have to use passthrough FC HBAs.
You've already got the logic to mount VMs from snapshots, would love to see that integrated into backups for a HotAdd-capable storage integration.
