===================
Filesystem overview
===================

PSMN provides access to several file systems, each with distinct storage characteristics. Each user and group get access to a set of pre-defined directories in these file systems to store their data.

.. IMPORTANT:: **PSMN is a computing center, not a storage center.**

    Storage resources are limited and are shared among many users. They are meant to store data and code associated with projects for which you are using PSMN's computational resources. This space is for work actively being computed on, and **SHOULD NOT BE USED AS A TARGET FOR BACKUPS FROM OTHER SYSTEMS**.

    If you're looking for a long-term storage solution for research data, CC-IN2P3 offers the iRods storage filesystem, which is specifically intended for this usage. Contact PSMN's Staff for access.


Those file systems are shared with other users, and are subject to quota limits and for some of them, purge policies (time-residency limits) :

.. danger::

    **There is no backup of the data stored on PSMN storages**. Any removed file is lost forever. It is the users’s responsibility to keep a copy of the contents of their storage in a safe place.

.. toctree::
    :maxdepth: 1

    access
    quotas
    storages
    home
    scratch
    transferts

Features and purpose
====================

+---------------+-----------+-----------+--------+--------------+---------------------------------------------+
| Name          | Type      | snapshots | quotas |  Performance | Purpose                                     |
+===============+===========+===========+========+==============+=============================================+
| ``$HOME``     | NFS       |       yes |    yes |  low, medium |        small, important files, source code, |
|               |           |           |        |              |            executables, configuration files |
+---------------+-----------+-----------+--------+--------------+---------------------------------------------+
| /Xnfs         | NFS       |       yes |    yes |  low, medium |    teams & groups files (same as ``$HOME``) |
+---------------+-----------+-----------+--------+--------------+---------------------------------------------+
| ``$SCRATCH``  | glusterfs |        no |     no |         high |         large temporary files, checkpoints, |
|               |           |           |        |              |                  raw temporary input/output |
+---------------+-----------+-----------+--------+--------------+---------------------------------------------+
| local scratch | ext4, zfs |        no |     no | medium, high | job specific output requiring IOPS [#iops]_ |
| (ssd, disk)   |           |           |        |              | (120 days lifetime residency)               |
+---------------+-----------+-----------+--------+--------------+---------------------------------------------+

.. important:: ``/tmp`` special case.

    All our nodes use `SIDUS <http://www.cbp.ens-lyon.fr/doku.php?id=developpement:productions:sidus>`_ OS distribution system. In that system, ``/tmp`` is located in :term:`RAM`. Do **NOT** use it to store files.
    (same apply for ``/var/tmp`` or ``/dev/shm``).


.. [#iops] See :term:`IOPS`