I'm new to the world of Ubuntu, and I've got a hard task to complete. I once created a Raid 1 bootable system with two 500 GB HDDs, I did it by following a guide with Ubuntu server (I think the version was 16). I followed the very same guide, trying to recreate a bootable Raid 1 system with two 4TB HDDs, which I need for a work assignment, but encountered a lot of problems. First it was the partitioning, then it was grub giving a critical error and failing to install on both drives. I tried many times to make it work but I am simply stuck on this. Is there anyone who can guide me towards a solution?