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Introduction to Systems

Storing data


In Windows, H: is mapped to your home directory on the file server which is reliable and does backups. The Desktop is mapped onto H:, but many other Windows app directories are copied back and forth from/to the file server when you login/out.


Under our Linux systems there are four ways to save data. Some of them are only intended for temporary storage and should not be used for data which is critical.

(same as ~/)

This is your home directory. It is the only place to store data which you wish to keep. Your home directory is saved by the backup system every night, but you have a limited amount which can be saved here. (To see how much you have saved and how much you are allowed to save, use the quota(1M) command. For more information, see below.)


Scratch uses the data area which remains on the hard disk of the local machine after after all other necessary items are installed on the disk. It is the right place to store large quantities of data which have been downloaded from the Web, or temporary files which are produced during the solution of a laboratory exercise.

The scratch area is not backed up, and its contents will be erased automatically when it begins to become full.


This area may be called a shared scratch. Use this area when you need to save something which should be accessible from a different computer from that which you are using right now; for example, if you want to install a somewhat larger program which does not fit in your home directory.


These are the wrong places to save large quantities of temporary data. This space is used by applications to save temporary data; if it becomes full these applications will function poorly or not at all. Therefore, do not use this area for other purposes than quick storage of smaller amounts of temporary data. This directory is emptied with each boot of the machine and older files are purged automatically while the system is running.

Accessing your data from remote

You can access them when away from the department, see https://webapps.cs.umu.se/files/.

Space in your home directory

The space which a student is allocated in the home directory is based upon the number of courses which that student is currently enrolled in. At this moment, the following limits apply.

  • A base limit of 300MB

  • A variable limit of 75MB per course

  • A max limit of 1700MB

    For example, a new student which hasn't registered on any course gets 300MB quota. A student who is on his/her 2nd year (has read approx. 8 courses) gets 300MB + 8*75MB = 900MB.

    For employees, quotas are used as a practical measure, to protected against runaway programs which would otherwise fill the disk with garbage. If you run out of space, speak with a system administrator to solve the problem.

  • Questions or problems? Send mail to: support@cs.umu.se