File systems

There are two main file systems on which users can store data: /home and /scratch.

/home (35 TB in total)

A directory /home/<username> is created for each user and all important results, scripts and other documents should be stored here. An incremental backup to tape of /home is made every night. In addition a full backup is carried out every 6 weeks.

In addition to the backup there are also copies of your data made at various points in time in the directory /home/<username>/.snapshots .  Data from the snapshots can be copied with cp just like any data back into your home directory.  NB: The directory .snapshots cannot be see with ls -a ! Also the tab completion in the shell will not work with this directory! However, the directory can be used as normal in a path, e.g. ls -l ~/.snapshots .

Writing a large amount of data very quickly to this file system can cause the system to become very slow and could even cause the whole file system to crash. Please contact us before attempting this.

/scratch (1.8 PB in total)

This is where temporary files, in particular large ones, should be created. This file system is particularly large and has the highest I/O-throughput. However, it is unsuitable for storing large amounts of very small files - in exceptional cases such files may be stored in your /home directory in a subdirectory called tmp. There is no backup for files on /scratch.

Showing available space

The 4th column ('Avail') of the output of the command df -h /home /scratch shows the amount of space still available on the file systems. Please be aware that the available space is a resouce which can be used by all users.