how can setup ns3 & ns4 and auto backup setup without any data loss

if ns1 & ns2 fail, how can setup ns3 & ns4 and auto backup setup without any data loss.

 

if you setup all NS in one server than, it makes no difference u have 2 NS or 4, if you are setting them in different server, than it might work better, for backup you can setup it tin whm, backup wizard, though to have proper backup, you need make sure your sites data are clean and not too big, if sites data is too big, usually whm can't backup them properly