How do I use the second SSD of my «EX40-SSD» Hetzner dedicated server in Debian?

What are the hardware specifications of «EX40-SSD» dedicated Hetzner server?

I use it as a RAID alongside with the first SSD:
2024-01-08--11-54-38

docs.hetzner.com/robot/dedicated-server/raid/software-raid

See also: