I recently had an issue with my boot drive (which has an lv on it) having space taken up by files on my mounted mdadm RAID0. I used ncdu / to determine this.
When I looks at blkid/mnt/md0 I saw that the raid was done using xfs.
So then I looked at /etc/fstab and it said it was mounted as ext4. So I changed the option in /etc/fstab, then ran sudo umount -a
Next I rebooted, and I saw that the issue of 72GB being taken up by /mnt/md0/ on the boot drive appears to be solved. Although I only gained 8GB of additional boot drive space.
The new issue that arose, more importantly, is that now I have both my RAID0 mounted at /mnt/md0 and my single 4TB drive mounted at /mnt/sdc and they both seem to be mounted inside themselves recursively. So that when I cd /mnt/md0/ I see another md0 along with all of the directories I expect to see. When I do cd /mnt/md0/md0 I see the exact same directory structure. The same holds true for the sdc drive mount point.
I have tried sudo umount /dev/md0 and sudo umount -l /dev/sdc (sdc was busy until I used the -l option)
Then rebooted the machine. This did not change anything.
What am I missing or what can I do to further troubleshoot and/or solve my issue?