How to connect a second hard drive in Hetzner?

Question

Debian

There is a long time rented EX6 dedicated server in Hetzner, on which there are 2 hard drives of 3 TB each. On a Debian 6 server. When installing the OS from the Hatzner image, it was possible to select a software RAID, but this was NOT done. Those. the system is on one of the disks, and the second one quietly hangs idle, and I, as a very inexperienced Linux user, don’t even know how to at least “see” it and check for operability.
In general, the task is to make a partition on it for backups from the first disk with minimal risks, so as not to destroy valuable information on the first one.
Where to start, what to use, how is it done in general? Describe, please, roughly, but as completely as possible, the path that I need to go through.

Answer 1

Create a partition table on the disk, create a file system on the partitions, mount it.
Or you can even not create partitions, just make fs on an unpartitioned disk.
Commands for learning fdisk (or parted, of your choice), mkfs (mkfs.ext4 probably, well, or whatever suits you better), mount (add a line to /etc/fstab by analogy with other sections).

Answer 2

google and study what is the difference between archiving, backup and fault tolerance, think about what task you really want to solve.
I also recommend that you study sequentially what is raid, what is mdadm, and how to migrate Linux to software raid1
and google what raid is
, you understand.
then google about mdadm
, read about, apply raid understanding to mdadm understanding,
then raise a virtual machine with one disk, install debian 6, turn off the virtual machine, connect the second disk, start the virtual machine, try to move to mdadm without data loss.