A problem with fstab and mounting hdds and permitions (I think)

I made a question few months ago about strange behavior of mounting process with fstab. Now I have a bit of new info, so I understand that the problem is with folders permission. But I can't catch this. So please help. As root I created folders:

/mnt/doc
/mnt/video

In my fstab I wrote:

# /etc/fstab: static file system information.
/dev/sdc1 /mnt/doc ext4 defaults,realtime 0 0
/dev/sdd1 /mnt/video ext4 defaults,realtime 0 0

And after reboot I have this:

● mnt-doc.mount                           loaded failed failed  /mnt/doc                                     
● mnt-video.mount                         loaded failed failed  /mnt/video

Now, if I do this:

sudo mount -v -t ext4 /dev/sdc1 /mnt/doc
sudo mount -v -t ext4 /dev/sdc1 /mnt/doc

Both drives are mounted without any problem...

  mnt-doc.mount                           loaded active mounted /mnt/doc                                     
  mnt-video.mount                         loaded active mounted /mnt/video  

So, I'm lost, please help.

Looks like a typo in your fstab-lines, I don't think that realtime is a valid mount option, use relatime which is a valid option.

You should not use device names like /dev/sdxy to define partitions in fstab. It's more reliable to use UUID or file-sytem labels although it doesn't seem to be the problem.