HomeAssistant Yellow: How to mount NVMe SSD as secondary drive

I recently received my first Home Assistant Yellow kit. I’m still a complete novice with Home Assistant, although I have been working within the ICT industry for decades, and have some system management as well as SW development experience from various Unix systems from early 1980’s till some 15 years ago. So, I do know the operating systems basics but have no practical experience about Raspberry Pis or Home Assistant.

I have 32 GB eMMC and a 256 GB NVMe SSD in my system. I first successfully installed HAOS in the eMMC, and after that I experimentally moved the “data disk” (which seems to include the operating system as well) to the NVMe SSD. Both went without any problems.

What I’d like to do now is to use the eMMC disk as the data disk and use the NVMe for backups etc. However I have not been able to figure out how to mount the NVMe as a secondary disk.

I first restored an earlier backup where my system was installed in the eMMC. At this point the NVMe disk was showing up only at /dev/nvme0n1p1 as expected.

I was thinking that I could simply create a directory /ssd1 and do a “mount /dev/nvme0n1p1 /ssd1”, which I executed as root. However I received an error message “permission denied”.

I wonder if anyone could shed some light on how to successfully mount the NVMe as a backup disk…