What is the solution for backup of the entire office + neighboring?

Question

Backup

there are 5 win + ubuntu servers, 20-30 office PCs and a couple of laptops for workers at home,
you need to somehow put everything together ... to make it easier to manage (or I already want a lot xs)
now I’m doing ubuntu via rsync on a separate hdd , AOMEI is installed on win servers, backups are made once a day. But for office PCs and laptops of workers .. trouble.
Who will advise what?
The advantages in this case will be:

• free
  
• on-the-fly backup (without rebooting and implementing a worker)
  
• the ability to backup to one server over the network or upload there after success
  
• the possibility of a simple rollback or a relatively simple one, for example, the computer completely died, it was deployed from the image for a certain date and we are working on
  
• work with win and unix systems
  

Answer 1

Regular backup is not bad - it is possible to create a disk image in the background.
Nix systems are worse with this.
In windows, if the channels are weak, and zpaq helps a lot to transmit.