Adapted from: http://faq.cpanel.net/list.cgi

If you get an email from your server or notice that a partition is near or at 100% full, check out some of the following possible solutions.

1. /var partition holds system log files. To see what directory/log is exhausting this partition , do the following:

• cd /var
• du -sh *
  this shows how much space is used/available in each directory as well as the file sizes of each file in the current directory.

The 'offending' file and/or directory should be fairly obvious. Once you see what directory is taking up all the space, cd to it and type the same command again; follow this pattern until you find the files taking up all the space. Once found, you can either delete the files or if you'd like to save some of the most recent entries to it, you can type this:

• tail -5000 filename > filename.new
• mv filename.new filename
  This will copy the last 5000 lines from the file to a temporary file.

2. /usr partition holds Apache files, including log files.

The first thing you should look at is the the apache log files.

• cd to /usr/local/apache
• du -sh *

Chances are you'll find that the logs/error_log or logs/access_log is very large. Feel free to delete them or use the tail trick above.