|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.
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 stork:/export2/users/z/zzzz07 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.
quotareports 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 -nThe largest files or directories will appear at the end of the list. The
ducommand 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
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:
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:
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
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!
Edit -> Preferences -> Advanced -> NetworkSet the disk cache to 0 and clear the disk cache.
core. These files can be quite large and should be removed unless you intend to use them. If you like you can prevent such files from being created by adding a line as follows to your
.cshrcfile in your home directory:
limit coredumpsize 0
rmcommand to remove all unnecessary files, especially the binaries, object code and backups. Binaries can aways be recreated if the necessary source code is available. If an exercise directory has a "Makefile" in it,
make cleanmay remove object code and binaries.
zipcommands. For example:
tar czvf <filename.tgz> <list of files to archive>
/vol/bitbucket/username; create this directory via
mkdir /vol/bitbucket/usernameif it doesn't yet exist. Files in other locations in bitbucket may be deleted at any time.
Bitbucket is available from Windows if you map the network drive:
You must not store any copyright material in bitbucket; both you and the College could get into serious trouble if so. Do not try to link bitbucket into your personal web pages.
pmount /dev/sda1to mount a newly inserted USB drive onto
pumount /media/sda1to unmount it before you detach the USB drive!).
Other Linux notes related to this topic are Managing your file space and Important files in your account.
|© CSG / Nov 2008|