after using the tutorial for how-to-create-raid-arrays-with-mdadm-on-debian-9, I was left with one step missing

Hi there,

Glad the tutorial worked well for you! Before making any changes, make sure you have a backup in case anything goes wrong:

https://docs.digitalocean.com/support/how-do-i-manually-back-up-my-droplet/

Once you have your backup, to move /home to your RAID 1 array you should be able to:

1. Mount the RAID array (if not already mounted):

   sudo mount /dev/md0 /mnt/md0
   

2. Copy /home data to the new array while preserving permissions:

   sudo rsync -aX /home/ /mnt/md0/home/
   

3. Update fstab to mount /home from RAID on boot:

   sudo cp /etc/fstab /etc/fstab.bak
   echo "/dev/md0 /home ext4 defaults,nofail,discard 0 0" | sudo tee -a /etc/fstab
   

4. Check if /home is on a separate mount:

   df -h /home
   

   • If /home is on a separate partition (e.g., /dev/sdX or another disk), you’ll need to unmount it first before updating fstab.
   • If /home is just part of /, they don’t need to unmount it, and they can proceed with remounting it from the RAID array.

   Before unmounting, make sure that there are no active processes running on /home:

   sudo lsof /home
   

   Once you’ve confirmed that there are no active processes, unmount /home and remount it:

   sudo umount /home
   sudo mount -a
   

5. Verify everything is working:

   df -h /home
   

6. Reboot and confirm that /home is properly mounted.

If anything goes wrong, you can revert by restoring from your backup and updating fstab again.

Let me know how it goes.

- Bobby