Niksula disk usage howto

Introduction

Niksula has a long history in providing a more or less relaxed computing environment for computer science students. There haven’t been too many rules as everybody has used their common sense.

As everybody has probably guessed, there is only a limited amount of disks in Niksula. Currently the limiting factor is the backup resources. So to avoid wasting them the administrators have placed a 10 GiB quota for all Niksula users.

Basic rules

1. If you happen to study the art of MP3 encoding or decoding, please store all your material in the scratch area (see below).
2. If you happen to study the art of file transfer, please remove your test material after your experiment.
3. If you happen to study the art of anatomy, please store all your material in the scratch area and practice the art of file transfer.
4. If you happen to study the black art of software piracy, please store all your illegal files somewhere else. Software piracy is a crime, and is strictly forbidden in Niksula.
5. If you really do need more space for your CS studies, please mail guru@niksula.hut.fi and the administrators might arrange some project space for you.

Determining disk usage

You can use the Unix command du -hs ~ to find out the disk usage of your home directory.

For a more detailed view of your disk usage, try the command du -sk .[^.]* * | sort -n. This will run du to all files and dot files on the directory and sort the outcome, so you can easily find the most disk space consuming files and directories.

One thing about du and networked file systems: du consumes lots of resources, so please avoid running it just for fun.

Restoring backups

You may restore files in your home directory to a previous point in time on your own by copying them from /home/.zfs/snapshot, which contains several snapshots of user home directories, including yours. NB: The /home/.zfs directory does not show in directory listings but is still accessible if you cd to it.

Where to store my temporary files?

When running large batch jobs, lots of data can be created and needed for a short time. If possible the temporary data should not be stored in your home directory. Please remove the temporary data as soon as possible!

Filesystems in Niksula

Your home directory, ~, $HOME

A place where NO temporary data should be stored! This file system is backed up frequently. You could store the final reports here.

Scratch, /p/scratch, /p/scratch/`whoami`

Data stored here is not backed up, but the filesystem is persistent and shared over the network.

/var/tmp, /tmp

These directories lie on the local workstation and are thus probably faster than the network filesystems. No backups are taken and files are stored for an unspecified duration (ie. may be removed at any time).

FAQs

• Why can’t I find the scratch directory in my home directory?
  • Say: ln -s /p/scratch/`whoami` scratch
• Why doesn’t my scratch directory exist?
  • The administrators haven’t created one for you. Please mail guru@niksula.hut.fi.