Usage/Quota

How usage is controlled

Introduction

To ensure fair-share usage and enable capacity based charging of the shared resources we limit your file space capacity via two mechanisms, depending on where the data is housed.

/vols/Data, group /vols/Scratch and /ohba/pi|projects folders are controlled at the file system size, user /vols/Scratch and home folders are controlled by user quotas.

Checking your disk usage

Per-share Limits

/vols/Data, /ohba/pi|projects and group scratch folders (/vols/Scratch/groupname) exist as individual file systems, so you can easily check on the current disk usage using the df command. Before you use this you must ensure the file system is available for interrogation, which you can ensure by changing into the share first:

3 jbloggs@clint1 $ cd /vols/Data/jbloggs
4 jbloggs@clint1 $ df -h .
Filesystem           Size      Used    Avail Use% Mounted on
fs2data-10g.data.fmrib:/volumes/Data/Shared/jbloggs
                      20G      612M      20G   3% /vols/Data/jbloggs

To get a breakdown of how your folders contribute to this disk usage, use the du command, e.g.:

du -sk .

will report the size of the current folder in KB

du -sh *

will report the size all objects in the current folder individually in appropriate units.

du -sk * | sort -n

will report the size of all objects sorted such that the biggest item is last in the list.

Where your group head has asked for quotas to be enforced on /vols/Data/* then you can check your quota usage using the quota command (see below).

Exceeding your disk space

The file system size controls enforced for these areas cannot be exceeded, and when reached it can be somewhat difficult to free up space again (a feature of copy-on-write file systems). Should you fill your area then you have two options:

Contact us to request additional space - please indicate whether you need a small increment to allow deletion or a permanent increase in space.
Find a large file you no longer require and issue the command:
```
cat /dev/null > thelargefile
```
This will truncate the file by-passing the copy-on-write mechanism allowing you to begin deletion in earnest.

User/group Quotas

Usage in home and user scratch folders is controlled using a quota system which is more relaxed in its enforcement of disk usage than the system used for /vols/Data - it is perfectly possible to slightly exceed your allocated space if writing occurs fast enough. To check your current usage use the quota command (on clint or OOD desktop terminal):

4 jbloggs@clint1 $ quota
Disk quotas for user jbloggs (uid 1234):
    File Space       Used  Available      Total
    /home/fs0   26.1 GiB    5.9 GiB     32 GiB
    /vols/Scratch   14.1 GiB   10.9 GiB     25 GiB

    N.B. Shared storage (/vols/Data or group scratch folders) is not
included in the above report - use 'df -h <foldername>'.

If you receive an error when running the quota command please try again, the server is most probably busy doing other things.

Miss-matches between reported quota and disk usage

The quota system records the size of all files and folders belonging to your account, no matter where they reside (for example in someone else's home folder), so it is perfectly feasible to have a reported quota usage that exceeds that of the contents of your home folder. If you find that du output does not match your quota report, look in locations that you may have shared files with others, e.g. if you have a shared analysis project with the files being stored in someone else's scratch folder then any files you wrote there will contribute to your quota.

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