How to use the 2nd hard drive?

Bare Metal and VPS
1

I use 4 dedicated servers of OVH, install RAI 1 with SSD 480 GB.
I use the OVH Dashboard and install servers, but there is no option to use the 2nd disk partition.
OVH has no documentation as well as they do not support.
How to use the 2nd drive?

2

You can't use the second drive when you install on RAID1, because both disk used for make a mirror. Reinstall OS on the first drive without RAID for use second drive.