Recently, I was working on a backup solution for a VMware vSphere environment. Veeam Backup and Replication was the software of choice. Veeam Backup and Replication is entirely based on disk-to-disk backup, but one of the customer requirements was to also have data on tape. For that reason, the backup server was a physical server, so it could be connected to a tape library.
The shared storage of the VMware cluster was based on iSCSI technology, in fact a couple of Dell PowerVault MD3000i boxes. In that case Veeam recommends for data retrieval the “Direct SAN access” mode. The operating system of the backup server is Microsoft Windows 2008 R2 Standard edition. The server has two NICs available for accessing the iSCSI storage.