How to organize a backup of the proxmox server?

Question

Backup

Hello, dear toasts: D
There is a physical server, Proxmox is installed on it, as many as 3 machines are spinning on Proxmox:
1. Windows server 2008-R2 (Read domain controller / file cleaner / DNS).
2.Windows server 2008-R2 (Read various kinds of legal software and bases for it).
3. Asterisk read SIP telephony server.
The server configuration is as follows:
Supermicro X9SCI / X9SCA
4 HDD WD BLACK motherboard - 2 for 1TB and 2 for 500GB (no raid!)
The question is of the following nature, the task was set to organize a backup of the server, so that in case of failure of one of the hosts nothing could be lost. At first, there was an idea to buy 2 HDDs for 3TB, combine them into RAID1 and transfer everything to this array (in case of a disk crash, just put a new one and that's it), but after scratching my turnips, I realized that this motherboard will not work with such large disks. How would you implement a backup of such a server? The volume is needed not less than 3tb. Thank you)

Answer 1

Duc backup or "in case of failure of one of the zhostik nothing to lose"?
These are two different tasks.
Why did you come to this conclusion?

Answer 2

take and backup to another server with 3 TB of space

Answer 3

Melkij :
And this, isn't it information about what raid is?