Quota and Disk Space

We operate disk quotas on home directories. To view your quota either use the command quota or hover your mouse over the quota app (described below) on your desktop. Home directory space is for important files that should be backed up.

When your disk usage reaches your quota you will not be able to save any more files in your homedirectory, nor update existing files.

If you are using MacOSX or Linux, the files in your Trash count towards your quota, so emptying the Trash is the first thing to try if you are running out of quota.

You can run the program cleanup to compress or delete uneeded files. To see how much space running cleanup could save you, run:

  cleanup -dummy

This will not compress or delete any files, just show how much space it might save.

The main reason we have disk quotas is because of backups. We regularly backup your file and the larger the volume of data to be backed up the shorter time we can keep the backups for.

Since September 2010 users of the DAMTP Linux Gnome (or KDE) and MacOSX desktops will have a small applet running to display quota information in a small region of the screen. On MacOSX and Gnome this will usually be near the top right of the screen, and on KDE near the bottom right.

On Linux the monitor shows a percentage as text and has a blue area indicating usage. The blue will rise to fill the box when as run out of space. Hovering the mouse over this will display more quota/usage information.

On MacOSX the monitor shows a small picture of a house with the percentage as text on it. Clicking on this will display more quota/usage information, and allow you to empty the Trash.

Windows users have had a similar quota monitor for some time in the status region to the bottom right of the screen.

All of these quota monitors will alert you when you are close to running out of space and allow you to quickly check your usage levels.

From the Linux command line you can check your quota at any time with the command:

  quota -v

If you are running close to your limit consider other ways of storing data.

• It can be stored on Data and Scratch spaces
• It can be copied onto a DVD/cdrom.
• Large or infrequently accessed files can be compressed with bzip2, gzip etc.
• directories of many files can be turned into an archive (e.g. tar) and then compressed
• Move some files you don't need to access daily to the Public Workstation Facility, you can then access these files from damtp via a web-browser.
• Archive some of your files to DVD or cdrom.

Where is all the space being used?

To see how much space you are using you can run:

  du -sk * .??*

That will show you how much space each file and directory in your homedirectory is using. If you find a large directory running

  du -sk directory-name/*

will provide a breakdown of file sizes in that directory, this can futher be extended in an obvious way:

  du -sk directory_one/directory_two/.../directory_n/*

You may find it more convinient to save the output of those du commands into a file (in /tmp say) and use sort -n on the result to show the output ordered by usage.

Can't find the big files?

If you are having difficulty tracking down the large files in your homedirectory space, a command like:

  du -ak > /tmp/du-$LOGNAME; sort -n /tmp/du-$LOGNAME

will list all the files and folders/directories in your homedirectory, and sort them by size from smallest to largest. Run this command from your homedirectory. It may take quite some time to display the files.

The command given above stores the results of the du -ak in a file in /tmp/ so you can examine it several times to look for several large files.

To check just the files in the top level of your home directory you could run:

  cd $HOME; ls -sa1 | sort -n

This will list your files sorted by size, but won't look in any directories/folders.

Useful Links

• All about your disk space
• How to write cdroms
• File Backups in Damtp

Quote Changes

To request a quota change please email help@damtp with:

• how much you want your quota to change by (increase/decrease)
• why you need a quota change

Quota Policy

If the home directory service becomes completely full then lots of computing and IT services will stop working or behave erratically. If the home directories become too large for our backup system then the frequency of backups will have to be reduced.

Home directory space is expensive (reliable, fail-over, fast, backups of various types including snapshots, archive, offline and offsite, etc.) and a shared resource.

Each request for a quota increase is judged on a case by case basis with the aim of balancing:

• needs of the whole Department (10% of user accounts should not be able to completely fill the home directory service)
• need of the account holder for space in which to store important data
• fairness between user accounts