We should move this to off topic really we're diversifying from the original OP's thread for which I apologise, I'll work out how to paste the link.
Looks as if I've managed to do it but going back to your answer @flmaxey confining the second xeon server might be a good idea, I've usually just backed up/copied across the network rather set up something up as a backup.
Having just installed OMV, the fact that everything is 'under one roof' is a bonus, but looking at a backup which just 'runs' without any hands on would be another. One option I had thought of was this as it has ethernet built in and doesn't have the restriction of usb, the one thing about wd mycloud is rsync.
TBH I had never heard of the Odroid until I came here, I have read reviews about the Asus and the Orange Pi, I suppose really it's horses for courses, what you want something to do and it's reliability.
At school I have 2 usb's for offsite and an old server for backup, I recently convinced the school to invest in Altaro because the standard windows server backup was failing more times than it worked, more from conflict with Attix 5 which was supplied by the local council as it backs up financial data to cloud storage (ms sql server).
I have Pi2+ in the lounge which runs Openelec with Kodi, connected via Powerline plugs rather than wireless.
I just checked the price in the UK for that 4TB WD Passport...around £140 or $180 .approx