/ directory thinks it's full when it's not

[Dynih]

I set up my Ubuntu file system so that my "/" directory sits in a partition of about 10 GB and my "/home/" directory sits in its own partition of about ~110 GB.

The "/" directory thinks that it has no free space (It says so at the bottom of the nautilus window when I'm in said folder, and if I attempt to copy something into it, it pops up with an error message to that effect). However, it's impossible for it to be full, as there's at most about ~4 GB of stuff in it. Furthermore, at such time, Flash videos won't play and I cannot install new programs from Synaptic. I am able to download files directly to my "/home/" partition, but cannot open them immediately (ie, I cannot download a .rar and have it immediately be opened by Archive Manager).

What seems to be happening is that the file system is including the size of "/home/" (roughly 6 GB currently) in its calculation of the free space of "/", despite "/home/" sitting on its own partition.

If I delete a sufficient quantity stuff from "/home/" so that the sum of "/home/" + "/" is <10 GB, Nautilus then does see a few MBs of free space in "/", and I am thus able to copy files to "/", Synaptic lets me install new programs, and Flash videos do play.

How do I fix this?

[woedend]

Not to insult your intelligence friend, but are you positive that your /home directory that you currently have files in is on its own partition, and not part of the root partition...ie, the /home 110 GB partition is not mounted, and you are using the /home folder within the root partition?

[Dynih]

No offense taken, that might be so.

I'm not sure how to check directly, but my biggest argument against that being so are, as I mentioned in the OP, that I can download arbitrarily large files to a location on my /home/ folder, but cannot do the same to my / folder.

[woedend]

you can post your /etc/fstab just in case and i'll take a look. Even simpler, unmount the /home folder either by umount or fstab and see if the free space changes. I've never kept /home on a separate partition, but I cannot see this as being a bug as it would be one HUGE bug.

[Dynih]

# /etc/fstab: static file system information.
#
#  -- This file has been automaticly generated by ntfs-config -- 
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>

proc /proc proc defaults 0 0
# Entry for /dev/sda6 :
UUID=f9388e61-27ac-4916-8294-cc26650113e2 / ext4 relatime,errors=remount-ro 0 1
# Entry for /dev/sda7 :
UUID=4131978e-24c2-4f06-a55a-678c2edcb8cb /boot ext4 relatime 0 2
# Entry for /dev/sda8 :
UUID=a5dffe28-0297-42d3-a8c4-dcd925b37210 /home ext4 relatime 0 2
# Entry for /dev/sda5 :
UUID=06b144a6-7ab9-4133-a84b-3465d72fe0e5 none swap sw 0 0
/dev/scd0 /media/cdrom1 udf,iso9660 user,noauto,exec,utf8 0 0
/dev/sda1 /media/Preload ntfs-3g defaults,locale=en_US.UTF-8 0 0

Is the fstab. Seems to show /home on its own disk, I think.

[bettlebrox]

Can you post the output from "df -h"?

[woedend]

indeed...your fstab looks to be setup correctly as far as I can tell. If you unmount /dev/sda8, does your full space return to normal? This is an odd problem...

[drs305]

You might have a look at this guide to finding why disks are full. It covers both GUI and command line methods. The most common things taking up unsuspected space are undeleted trash, backups made in the wrong place, and large log files.

A misplaced backup might be the first thing to look for. Unmounting all non-system drives (sudo umount -a) after closing all apps sometimes reveals the problem, since mounting a partition conceals anything previously on the mount point.
HOWTO: Recover Lost Disk Space