Department of Computing Imperial College London
Disk quota and temporary storage space

There is a limit on the amount of disk space on the fileservers which students and staff are allowed to use. This is known as disk quota and (from October 2005) is set at 500MB for everyone in DoC. This quota covers any files and sub-directories created in your home directory, including all your email. Your home directory is your initial working space when you log in to any Linux system, and is the area known as the H: drive on Windows systems.

Checking your quota and disk space used

You can check your quota and the space you are using by typing:


on any Linux system. The only way to check your quota when running Windows is to log in to a Linux host via an ssh client (eg. putty) and run the quota command as above.

The output will be similar to:

Disk quotas for user zzzz07 (uid 9999):
     Filesystem  blocks   quota   limit   grace   files   quota   limit   grace
                  22400  500000  600000              18   20000   21000

This shows you the various file spaces on which you have a quota. In this example, the user's home directory is held on a filesystem called /export2 on the file server stork, the user is using 22MB (megabytes) of disk space at present, has a quota of 500MB and a hard limit of 600MB. This user would start getting warning messages when they pass 500MB, and would never be allowed to use more than 600MB. The user also has 18 files, and is limited to 21000 in total.

Which files are taking up most space?

People often think they are only using say 20MB of space and when quota reports they are using 50MB they don't believe it! The truth is that many applications you use store data in files you don't even realise are there. Email can also take up a lot of space.

The following command will show which files are taking up most space in your account:

du -s * .[a-zA-Z]* | sort -n
The largest files or directories will appear at the end of the list. The du command can summarise disk usage in various ways - see the manual page (type man du) for other options.

You might want to add that command to the end of your .cshrc file as an alias:

alias usage 'du -s * .[a-zA-Z]* | sort -n'
then on future logins (or immediately, after running source ~/.cshrc) you can simply type:

What happens when I go over my quota?

Suppose you have a quota of 500MB, with a hard limit of 600MB. This allows you to store up to 500MB at all times, and allows you to exceed 500MB (up to an absolute upper limit of 600MB) for up to 7 days at a time. When you exceed your quota, quota will show a timer that starts counting down to zero, and you must delete enough files to come back under quota before the counter expires.

If you either hit your hard limit, or allow the over-quota timer to expire (i.e. leave yourself over quota for a whole week) the consequences will be:

How can I reduce my usage once I have reached my hard limit?

If you reached the total amount of disk space you are allowed to use you will not be able to log in via X-windows (KDE/Gnome). This is because the system creates a temporary file in your account when you log in. If there is no space to do so, you can't log in. You can log in if you avoid X-windows.

On Linux workstations type Ctrl-Alt-F1 to get a text-mode login prompt. Log in, find where you're using the space (usage alias above), then clear some space by removing or compressing files until your quota comes under the soft limit, using the command quota -v to check). Then log out of the text-mode login, and then press Ctrl-Alt-F7 to return the machine to X-Windows, and login in graphically.

You can also clear space by logging in via Windows and removing files from the H: drive. Take care not to remove any Linux setup files!

Making the most of your quota

There are several recommended methods for getting the most out of your file space.

Other storage areas

Getting your quota extended

The disk space quota is considered adequate for most academic work and you would need a good reason to be allocated any more (eg. final year project work involving video streams:-)). You're welcome to email help@doc however and ask. Shared disk space is set up for group project work. We sort this out directly with the group project organiser and will email students with group project info when we have the data.

Other Linux notes related to this topic are Managing your file space and Important files in your account.

© CSG / Nov 2008