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===== Basic information about the Cluster ======

These are things one should read before using the cluster.

==== Cluster components ====

The cluster is currently composed of the following:

  * Two **nodes for interactive access/testing**: they allow users to run interactive jobs. More about them can be read in [[iridium_cluster:testnodes]]
  * A **storage server**: used to maintain user home folders, software and data. See [[#Common files organization]] below for details.
  * A **batch processing** inrterface: allows researchers to run many jobs and schedules them in a fair way using the [[http://www.nordugrid.org/arc|ARC software]]. It manages the cluster nodes.
    * **10 nodes**: these are machines where you will actually run your code. Currently they can be directly accessed, but in the future this will change. The **batch processing** interface will be the only entry point. 
    * Each node has:
      * a simple name: //nX//, where //X// is the number of the node. i.e. //n1// is node number //1//.
      * 16 cores
      * 64GB of RAM
      * access to all folder served by the storage server. This means that a researcher will have her own home folder regardless of the node she's logging in.
    * the **gateway** was used for users to access the cluster, but now will be phased out or allocated for other purposes.

To access the cluster, you'll need an account on it.
Contact [[:Florido Paganelli]] or Pico to get access.

==== Common files organization ====

Every node of the cluster can access the shared storage. All users can access the shared storage, but can only access areas assigned to the working groups they belong.
The shared storage is organized as follows:
^ Folder name ^ Folder location ^ Folder purpose ^ expected filesize ^ Description ^ Subfolders ^
^ users | ''/nfs/users'' | User homes | files smaller than 100MB each | This folder contains each user's private home folder. In this folder one should save his own code and eventually private data. Data that can also be used by others and the single files are bigger than 100MB should **not** be in this folder. Use the **shared** folder instead. | /<username> each user her own folder|
^ ::: | ::: | ::: | ::: | ::: | ''/npguests/<username>'' for Nuclear Physics guests |
^ ::: | ::: | ::: | ::: | ::: | ''/ppguests/<username>'' for Particle Physics guests |
^ **software** | ''/nfs/software'' | Application software  | files smaller than 100MB each | This folder hosts software that is not accessible via cvmfs (see later). This usually includes user/project specific libraries and frameworks. | ''/np'' for Nuclear Physics users |
^ ::: | ::: | ::: | ::: | ::: | ''/pp'' for Particle Physics users |
^ **shared** | ''/nfs/shared/'' | Data that will stay for long term | Any file, especially big ones | This folder should be used for long-term stored data. For example, data needed for the whole duration of a phd project or shared among people belonging to the same research group. | ''/np'' for Nuclear Physics users |
^ ::: | ::: | ::: | ::: | ::: | ''/pp'' for Particle Physics users |
^ **scratch** | ''/nfs/scratch/'' | Data that will stay for short term | Any file, especially big ones | This folder should be used for short-term stored data. For example, data needed for a week long calculation or temporary calculation. This folder should be considered unreliable as its contents will be purged from time to time. The cleanup interval is yet to be decided | ''/np'' for Nuclear Physics users |
^ ::: | ::: | ::: | ::: | ::: | ''/pp'' for Particle Physics users |
^ **cvmfs** | ''/cvmfs'' | Special folder containing CERN maintained software | user cannot write | This special folder is dedicated to software provided by CERN. This folder is read-only. Usually the content of this folder are managed via specific scripts that a user can run. If you need to add some software that you cannot find, contact the administrators. | ''/geant4.cern.ch'' for Nuclear Physics users |
^ ::: | ::: | ::: | ::: | ::: | ''/atlas.cern.ch'' for Particle Physics users |

==== User groups ====

Five main UNIX user groups are defined, as follows:
^ User group ^ Who belongs to it ^ Group hierarchy ^
^ npusers | Researchers belonging to **Nuclear Physics** | primary |
^ npguests | Visitors belonging to **Nuclear Physics** | primary |
^ ppusers | Researchers belonging to **Particle Physics** | primary |
^ ppguests | Visitors belonging to **Particle Physics** | primary |
^ clusterusers | All users accessing the cluster | secondary only for npusers and ppusers |

Group hierarchy tells how your files are created. Whenever you create a file, its default ownership will be:
  * user: your username
  * group: group you belong

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