If an administrator run a VIOS within IBM i environment only, he needs to do backups anyway.
The most efficient way how to do it, is perform backups to a NFS file system exported by an IBM i .
To do so, in the System i navigator
Network -> Servers -> TCP/IP
Start NFS Server, and add a specific directory to the NFS export list. (Righ click Exports).
Now, from the VIOS shell you can mount the export directory, and perform a backup command to the remote file system.
If an administrator run VIOS environment without a NIM server, and the restore operation would be perform from a HMC, I suggest a command:
backupios -file /mnt/backupfile -nomedialib
Having this, an administrator stores VIOS backups on the IFS of an IBM i. Now its enough backin up the IFS together with libraries from a system i.