It might be better to “pull” things from a server for backup , but pushing is much easier to setup. So … I looked into things and connecting to  a Z drive COULD be dangerous. One Encryption-Ransomware makes it a first priority to kill off the backup drive, then encrypt the files. So any drive that is connected as a Z drive (for example) would either be encrypted or wiped. So how best to protect? Well what about (s)ftp? Better, but it could overwrite old backups. So 2 fold … backup NOT via SMB and then have a 2nd “last backup” as well. Drop box does this  but it is expensive to have dropbox for that large and to have ‘history’ turned on – but it DOES WHAT WE NEED!! What I did was install WinSCP and have it use a queue and when the queue is empty – it shuts WinSCP down. Simple, drag and drop. Yes it is not automatic, so what i have is the backups being stored on a simple hard drive – the WRONG way, but then I take that backup and WinSCP it off as my historical copy alongside the other historical folders. That 2nd computer, if there is a fire, should be offsite or across the building minimizing the chances of a complete disaster. Beats tape rotations. Fire safe, secure, encryption proof (within a week) and an offsite rotation if the customer wishes by taking the local hard drive weekly (if you can find the J personality style who will do that religiously)