Krdytkyu

I have only one disk in my computer, a 80 GB SSD. It is formatted as a single ext4 partition (no swap), and all the usual folders are installed on it (I keep lots of data on external media, but /home and all the rest is on the SSD).

Today I booted it and I got a message that the drive is full. I opened Disk Usage Analyzer to look at what takes up space. It insists that 67.8 GB of the disk are used, and that / is taking up 36.4 GB. Which leads to the question, where are the missing 30 GB, if not on the file system?!

Just to have a comparison, I added up all the sizes of all readable folders listed in Nautilus as subfolders of / (including the hidden ones). I got 20.9 GB. Trash was unreadable, but I know it has 16.2 GB, so the sum is 36.1 GB, around the same as what Disk Usage Analyzer is reporting. There were some system folders which were unreadable, like proc, but I doubt that they add up to 30 GB - else it wouldn't be possible to install Ubuntu on small disks, and I've seen it run on 2.5 GB. I think they must be the 0.3 GB difference between my calculation and the Disk Usage Analyzer's report.

So I'd like to know, what is eating up these 30 GB and how do I get it to free them?

Edit with answers to CYREX's questions

1. 
   

   Booted from Ubuntu 10.10 64 bit live CD (same as my system).

   
   
   

   fsck result:

   
   
   

   root@ubuntu:~# fsck /dev/sda1
   
   fsck from util-linux-ng 2.17.2
   
   e2fsck 1.41.12 (17-May-2010)
   
   /dev/sda1: clean, 265956/4890624 files, 18073343/19537408 blocks
   
   

   
   


2. 
   

   Booted from the SDD. Emptied the trash, and the 16 GB from there are now free. The 30 GB are still missing.

   
   
   

   

   
   


3. 
   

   I am not experienced enough to know what counts as weird in a log. Here are my messages log and my syslog since last boot, maybe you can find something in them:

   
   
   
   
   
   • http://pastebin.com/FHrrV1rR
   
   
   • http://pastebin.com/FK8TmZbc
   
   
   
   


4. 
   

   Here it got really strange. I plugged in an external 500 GB HDD. Disk Usage Analyzer overreported the available space, then showed space missing (76 GB used, but only 24 in folders).

   
   
   

   

   
   

Booted again from the LiveCD, started the Disk Usage Analyzer from it and got the same results as from the installed Ubuntu, within 1-2 GB.

Edit with answer to CodeMonk

That would have been a nice solution, but the partition is really 80 GB - I mean 74 GB + marketing "error", anyway the whole disk is formatted. It also shows that over 50 GB are used - so where are the 30 GB if not in files and folders?

GParted also reports the correct size of the external HDD.

If you use Disk Analyzer as a normal user there can be some files that you can't access or see. You can try to start it with superuser privileges. Open a terminal, or press ALT+F2 and type:

gksudo baobab

Baobab is the geeky name of the Disk Analyzer if you are wondering. Maybe it can now show you where those missing megabytes are.

I solved it - thanks to all your advice, especially that of Javier Riveira, who suggested running Disk Analyzer with sudo rights (I didn't know this can have influence on the results).

I have Crashplan, and it is making backups to some of the external drives. So there is a backup set which goes to Milly, and another one which goes to Sto_Lat, once every 15 minutes (these are the names of the external drives). When I have at some point started the computer without these drives, Crashplan has found no folders under /media/Milly and /media/Sto_Lat, so it has just created them and has written backups to them.

For some reason, Disk Analyzer does not show these folders when started without sudo. Nautilus shows them, but lists the size of /media at 16 KB, when it is actually 30 GB.

I only noticed this when I dismounted all external drives, including Milly and Sto_Lat, and started gksudo baobab. Then I saw my external drives where there should be none - but not all of them but only the backup targets - and realised that these are not mounted drives, but eponymous folders created by Crashplan. There must be something weird going on when I mount the drive at the same name as the existing folder, I wonder why I don't get an error message or something...

BTW, this also solves why Disk Analyzer shows the sizes of Milly at 530 GB instead of 500 GB - these are the "missing" 30 GB, it counts the folder and the real drive together.

Now I only need a way to delete the folders without breaking Crashplan or remaining without backups.

You can use the Disk Usage Analyzer to scan your directories and see where your space is going on the filesystem.

As for not being able to see 30GB of your disk, open up GParted and see how the space is allocated on the disk. It may be that your partition scheme isn't what you thought it was.

You can use du to show this:

cd /

sudo du -hcsx .[!.]* * | sort -rh | head

or

sudo du -hcsx * | sort -rh | head

This will show what is using the most space.

As default there are 10% of your disk space reserved for the root user. You can change that using sudo tune2fs -m %percentage %device. In your case that would be sudo tune2fs -m 1 /dev/cciss/c0d0p1 for reducing the reservation to 1%. You can set it to any other number you like but I would not recommend 0%.