FreeNAS backup solution using rsync and virtualbox

I used the FreeNAS as file server  for about 50 users and the freenas works stable as a rock from 2008 till now,which was based on a hp desktop dc5700 with 1G ram and 140G disk volume.However,with the data increasing and time went by, the stability was the most important stuff I need to consider about,so I made the backup solution to work as primary/standby to shorten the MTTR which use RSYNC,vm tech..
because I only have few days and limited resources, so maybe the solution seems a little rough…anyway,it’s ok,just change the ip will finish the taking over and the bussiness is not so real-time.