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Storage and quotas

In our network you will encounter disk quotas for Unix OS and Windows OS machines.

Unix

On Unix machines, each user has the following storage available to them and is limited by a disk quota:

  • on the /home/login volume with the home directory, which is located on the home.fi.muni.cz machine and is exported using NFS and SMB protocols; the storage is backed up
  • on the /data/login volume with user data, located on the home.fi.muni.cz machine and exported using NFS and SMB protocols; the quota is an order of magnitude higher than on the home directory, but the volume is not backed up and access to it may be slower
  • on the aisa.fi.muni.cz machine on the /var/spool/mail mail volume (does not apply to employee mailboxes on the Anxur machine)
  • on the aisa.fi.muni.cz and anxur.fi.muni.cz machines on the /tmp and /var/tmp volumes for temporary files

See also the remote connection options for these repositories.

If you are interested, you can read more about the disk storage solution in our blog post.

The quota limits the space taken up on disk and also the number of files stored. The limitation of each of these resources is given by soft quota, hard quota and time limit, the meaning of which is as follows. Once the soft quota is exceeded, the user is given a time limit until which he can work normally. However, the system alerts him/her when the quota is exceeded - a notification mail is sent and the notification is also displayed in the command listing quota (see below). After the timeout expires, the user is restricted from accessing the volume with the exceeded quota (it is not possible to create new files or increase the size of existing files), and the user must delete a sufficient amount of data and/or files to regain access. The system will not allow a hard limit to be exceeded. If an operation causes the hard limit to be exceeded, it will not complete and will exit with an error.

Determining quota status

All limits set on volumes can be found in Faculty Administration under My Account - Overview. You can find out the current occupancy values and space and file limits on a particular machine by entering the command quota. Example:

aisa$ quota
Disk quotas for user login (uid 55555):
Filesystem       space   quota   limit  grace  files  quota  limit  grace
/var/spool/mail  12K     147M    176M   0      2      50     100    0
/var/tmp         0K      1954M   3907M  0      0      50000  80000  0
/tmp             4K      1954M   3907M  0      2      50000  80000  0
/home/login      47408K  3907M   4883M  0      5841   160k   200k   0
/data/login      4K      97657M  144G   0      2      600k   700k   0

nymfeXY$ quota
Disk quotas for user login (uid 55555):
Filesystem       space   quota   limit  grace  files  quota  limit  grace
/home/login      4882M*  3907M   4883M  6d     5841   160k   200k   0
/data/login      4K      97657M  144G   0      2      600k   700k   0

The examples show quota discovery on the Aisa and Nymph machines. The first three columns indicate the size, followed by the grace period, and then the same for the number of files. For Aisa, you can see the quotas for the volumes /var/spool/mail, /var/tmp, /tmp and then /home/login and /data/login.

The second to last row mentioned is usually the most important, as it shows the quota information on the home directory.

In the second example, we then similarly see first the quota on the home directory and the quota on the /data/logindirectory with user data. This example also shows how the quota command informs you when the quota has been exceeded. The exceeded number is followed by an asterisk and the grace column shows the running timeout.

When the quota is exceeded

When a quota is about to be exceeded, we automatically send a message to the faculty address. When the quota is exceeded on the aisa:/var/spool/mail volume, the mailbox is moved to the home directory and the user is also notified by a message.

If the quota on the home directory is exceeded, then logging into the system using the graphical interfaces may mysteriously fail. However, if you do not encounter a hard quota on the home directory and have not timed out after exceeding the soft quota, you will be notified of the quota problem and also notified by email. However, logging in via the text interface ( Ctrl-Alt-Fn) or SSH should always work for you.

How do I find out which files are taking up the most space

Log in to your account (e.g. using ssh) and run the command line:

$ du -kax | sort -n | tail -n 10
323316  ./.cpanm/work/1329993381.18167
340828  ./mail/misclass
350480  ./.Spotlight-V100/Store-V1
350488  ./.Spotlight-V100
367740  ./.cpanm/work
367820  ./.cpanm
414276  ./prog
627336  ./.ccache
2420912 ./mail
7762344 .

This command will list the used space in kB in all directories and files (even hidden ones) in your home directory, organize them by size, and list the 10 largest. Or you can also use the interactive tool ncdu:

$ ncdu

In this case we could delete some unnecessary files:

$ rm -rf .ccache .cpanm/work

You can do the same for the /data/login volume , but you need to switch to it before executing the du command:

$ cd /data/login
$ du -kax | sort -n | tail -n 10
...

However, the above command du may not always reveal the cause of a full quota. The listing will only show the space used by the files in the directory, but the quota is calculated over the entire volume ( /home or /data) and the owner of the file is decisive. If the data from the quota and du listings differ significantly, it may mean that some files owned by the current user are located in another user's directory (or vice versa). In this case, you need to remember where they may be located and, if necessary, ask that user to access/remove the files. If you have tried the options listed here and are still not sure, contact the administrator at unix@fi.muni.cz.