Amazon EC2 - disk full
Well, I think its one (or more) logfiles which have grown too large and need to be removed/backupped. I would suggest going after the big files first. So find all files greater than 10 MB (10 MB is a big enough file size, you can choose +1M for 1MB similarly)
sudo find / -type f -size +10M -exec ls -lh {} \;
and now you can identify which ones are causing the trouble and deal with them accordingly.
As for your original du -a / | sort -n -r | head -n 10 command, that won't work since it is sorting by size, and so, all ancestor directories of a large file will go up the pyramid, while the individual file will most probably be missed.
Note: It should be pretty simple to notice the occurence of similar other log files/binaries in the location of the files you so find, so as a suggestion, do cd in to the directory containing the original file to cleanup more files of the same kind. You can also iterate with the command for files with sizes greater than 1MB next, and so on.
If you are not able to find any gigantic file , killing some processes might solve the issue (it worked for me, read full answer to know why)
Earlier:
/dev/xvda1 8256952 7837552 0 100% /
Now
/dev/xvda18256952 1062780 6774744 14% /
Reason:
If you do rm <filename> on a file which is currently open by any process, it doesn't delete the file and the process still could be writing to the file. These ghost files can't be found by find command and they can't be deleted. Use this command to find out which processes are using deleted files:
lsof +L1
Kill the processes to release the files. Sometimes its difficult to kill all the processes using the file. Try restarting the system (I don't feel good, but that's a quick solution, makes sure no process uses the deleted file)
Read This: https://serverfault.com/questions/232525/df-in-linux-not-showing-correct-free-space-after-file-removal/232526
At /, type du -hs * as root:
$ sudo su -
cd /; du -hs *
You will see the full size of all folders and identify the bigger ones.