How do I get Linux to recalculate disk space?

My root filesystem was full. It isn't anymore.

However, when I boot the sytem, Root filesystem has insufficient free space is logged. Other error messages indicate the same problem. Moreover, df reports that the root partition is still full. So does df on a live distro.

I'm open to any solution. I can do with the box whatever I want.

Distro: Debian Wheezy.

The problem is gone and I cannot explain why. All I did was copying about 100GB from to another disk. Now, any indication of a filled up root filesystem is gone. I would really like to give more to the community, but I simply cannot determine the solution.

closed as off-topic by Sparhawk, G-Man, countermode, Jeff Schaller, roaima Apr 20 '17 at 13:40

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions describing a problem that can't be reproduced and seemingly went away on its own (or went away when a typo was fixed) are off-topic as they are unlikely to help future readers." – Sparhawk, G-Man, countermode, Jeff Schaller, roaima
If this question can be reworded to fit the rules in the help center, please edit the question.

  • 7
    It sounds like it's still full then... – Kusalananda Apr 19 '17 at 17:25
  • Since it is still full after a remount (reboot), then the actual file usage would be visible in the directory tree. In your current situation, you'll obviously need to boot in single user mode or from another partition/device to clarify and clean it. – Julie Pelletier Apr 19 '17 at 17:33
  • 1
    Use a bind mount to find hidden files on /: unix.stackexchange.com/a/358331/30851 – frostschutz Apr 19 '17 at 18:20
  • 1
    Please show the output of lsblk , df -Th and fdisk -l or parted /dev/sda print. Also is this an LVM type? – Valentin Bajrami Apr 19 '17 at 18:22
  • @Julie_Pelletier: The problem persisted in SU mode. – user2964971 Apr 19 '17 at 20:14