Hi, I advise you to install another HDD / SSD on your server. This is better for you to be protected if your hard drive is broken. If you prefer to make a backup on the same disk, you should create a new partition, but I do not think that 200 GB is enough to make an 800 GB backup.
Ok, sure, so here's what I'm looking for:
Dedicated server (BackUp Server): 2TB HDD,
2 remote servers (installed with java, tomcat, linux), each with 1 TB of hard disk space.
Now, how to configure them, so the backup runs every 24 hours (backup programming option) on each of the remote servers and is stored on the backup server (separate dedicated server).