Nextcloud, Raspberry and raid 1

[gas85]

Welcome to forum!
I believe this is not really a topic of this Forum. Quick search will drive you to something like this:

@gas85

Have similar setup, you can see it here Optimal hard disk setup on Ubuntu 2 x SSD (Raid1) + 2 x HDDs (Raid1) few commands are also in a tread → Optimal hard disk setup on Ubuntu 2 x SSD (Raid1) + 2 x HDDs (Raid1)

Exact installation depends on your needs and HW.