When you look at the sixth field in your /etc/fstab, you see there a 0. This means the mhddfs is not automatically fscked. So one workaround of your problem is to add noauto to your fstab:
mhddfs#/storage/HDD/SAM-2000-1/Medias,/storage/HDD/SAM-1500-1/Medias,/storage/HDD/SEA-1000-1/Medias,/storage/HDD/SEA-1000-2/Medias /storage/BigData/Medias fuse defaults,allow_other,nofail,noauto 0 0
So the filesystem will not automatically mounted at startup. Furthermore you write a script which basically mounts your mhddfs and add it at some late point in the boot process.
This makes sure that the fsck runs normal. If your system tries to mount the mhddfs, all other fscks are finished and your system should boot normal.
Best not to use /mnt, but create a new /mnt/data or just /data. You may want other mounts in /mnt and those would remove the data partitions (I have done that in testing a /mnt of something).
After you copy all your data folders like Music to the partition on your other drive.
Unmount your temporary mount if it is just temporary.
NOTE: The mount point can be anywhere. If it's in your /home or /media folders it will show up under "Places". If it's directly off "/" or /mnt it will not. I prefer /mnt so I do not see it other than thru the links.
sudo mkdir /mnt/data
sudo chown $USER:$USER /mnt/data
sudo chmod -R a+rwX /mnt/data
Note: The big "X" will also not make files executable unless they were executable to begin with.
find your UUID, entry below shows example with UUID, must be yours
sudo blkid
Edit fstab with your UUID, use ext4 or depending on format:
sudo -H gedit /etc/fstab
UUID=a55e6335-616f-4b10-9923-e963559f2b05 /mnt/data ext4 relatime 0 2
Verify entry is ok, if no errors it is, if manually mounted as above unmount first:
sudo mount -a
from home (cd ~ if not at home) so default location of link is in /home/$USER
cannot have duplicate entries, so move current to temporary location, repeat for each folder you want to move.
mv Music oldMusic
Music is then also the folder in the partition mounted as /mnt/data
ln -s /mnt/data/Music
Or link all folders with one command:
for i in echo /mnt/data/*;do ln -s $i; done
You can delete oldMusic after you confirm everything is ok.
it then should be this with l as first char for link.
fred@Z170N:~$ ll
lrwxrwxrwx 1 fred fred 15 Jun 10 2017 Music -> /mnt/data/Music/
Best Answer
Systemd has now included a dependency option that enforces mount ordering. In your case add the fstab arguments:
The noauto option will not work if you need to mount over other mounted file systems. In my case the above worked see commit https://github.com/systemd/systemd/commit/3519d230c8bafe834b2dac26ace49fcfba139823 for more details.