User's Guide



Before using the CC computing resources, you are kindly asked to read the charter of good practice of Computing Centre resources . The knowledge of the content of the charter is a legal request.

To get an account, please refer to the document to request the opening of a local account at the Computing Centre .

How to proceed in summary :
If you have no account at CC, you have to fill a request to access to the resources of CCIN2P3. You can fill it on-line providing an account name, your experiment or laboratory name and a valid e-mail address. You then print the request, sign it and give it to your CZAR (the person registered at CC as being responsible for your experiment or laboratory). After his signature, the CZAR will fax it to the Centre to end up the procedure. Once the account is created, the CZAR will be informed and will provide you with your password.

For more information on CZARs, please consult the document: Users with administrative privileges(CZAR)

The computing infrastructure of the IN2P3 Computing Centre is composed of heterogeneous hardware assigned in four categories:

  • the CPU platform
  • the disk storage platform
  • the mass storage (cartridges / tapes) platform
  • the set of servers dedicated to each service

Please keep in mind that the resources are shared between many users and many experiments. Therefore it is important to optimize their usage.

How to connect to CC

You can connect to the Computing Centre via SSH on the interactive computing farm. To connect, you can use a graphical application with a SSH client. Or you can connect in command line:

> ssh <UserAccount>@cca.in2p3.fr

You are requested to type your password.

For more informations on how to connect to CC, please consult the document: Your working environment .

How to change password

To change your password, the command is:

> kpasswd

The password is valid for 180 days. The password must conform strict rules in order to get accepted when you change it: it must have at least 12 characters of 3 different types (lowercase, uppercase, numeral or special character)

If you have forgotten your password, please contact your laboratory CZAR (CZAR for accounts) .

The CC neither provides the password, nor modifies it.

How to forward your e-mail account to your favourite address

When your account is created at CC, the mails are sent by default to the e-mail address provided during the registration. If your default account is not at CC, you can redirect the mails sent at <YourAccount>@in2p3.fr to your usual mail box.
To redirect your mails contact users support

The Computing Centre provides different storage systems allowing to work in a shared way within a group or a collaboration.

The different storage system can be classified in two categories: systems accessible from standard UNIX commands systems accessible with proprietary interfaces or commands

The two systems accessible from standard UNIX commands are the AFS space and the semi-permanent storage zone called SPS. These two storage spaces are easily accessible by different softwares compatible with UNIX environment.

However a great number of groups needs to process and produce scientific data which volume can be substantial. Management of these data are often done through the storage robot on magnetic cartridges. Stored data on this kind of media are accessed by different technologies following the needs specified by user groups.

To optimize the use of these systems as part of a big use, it is necessary to first get in touch with Computing Centre staff. A constructive exchange of informations will allow to adopt the best strategy and to reasonably size the needed systems.
The aim of the Computing Centre is to optimize data access performance at the lowest cost and to limit lost CPU time when waiting for data access. This is to increase the performances of your jobs and of your scientific data processing.

AFS shared file system

AFS file system allows to share files between different machines of the Computing Centre. AFS has its own access control list (ACL) on directories. AFS rights are “higher” than standard UNIX rights.

A user with an account at Computing Centre can access 2 zones: its AFS “home” directory accessible through the variable $HOME. In general, this space allows to store personal files which one can put either in “public” directory or “private” directory the “throng” directory ($THRONG_DIR) is set aside for software installations at group level

Be careful, only the $HOME and $THRONG_DIR directories are daily backed up. To know more about the backup policy at Computing Centre read the article "AFS: backup of the different AFS spaces"

SPS semi-permanent storage space system

Files with lifetimes of order of weeks/months can be stored on semi-permanent working space (SPS) . These disks are basically dedicated to data analysis of some weeks. There is no backup of the data and these can be erased if it is not used or in case of lack of storage space.

Data management on cartridges

You might want to store your data directly on cartridges. At CC, files on cartridges are managed with RFIO through HPSS storage system: HPSS : **H** igh **P** erformance **S** torage **S** ystem , is a high performance mass storage system able to store large volumes of data. RFIO : **R** emote File Input/Output is a package which allows the user to access non local files. RFIO is used for HPSS access

Data access through cache systems

For the experiments that need to access an important volume of data stored on cartridges, it is very efficient to use data cache systems in front of the mass storage system.
The Computing Centre have two technologies: DCache Xrootd

Data access through virtualized storage systems

You can also store your data through virtualized storage system. This allows to hide from users type of media on which the data are stored: iRODS

There are different ways to submit your jobs: interactively by remote logging. This interactive mode is used to develop algorithms and for short jobs (in the order of 10 minutes) in offset mode using the batch system Grid Engine from the GRID through EGEE facility

Batch job submission using Grid Engine

Besides the machines on which users can connect and that they can use interactively, the Computing Centre has a big set of workers dedicated to intensive CPU usage, for scalar and parallel computing, see Informations about Grid Engine batch system computers at IN2P3 Computing Center .

Users cannot connect directly to these computing machines, but can submit their jobs from the interactive machines through the batch system Grid Engine using a command such as:

> qsub [ options ] [ file name ]

see Using the GE batch system at the computing centre .

This “standard” type of submission is only possible provided you have an account at CC. This is a local job submission; another type of remote submission through the GRID (see below). Once the job has been sent, GE allows to eventually alter and to follow it through its completion.

Computing farm resources are shared between several users from different groups and experiments. In order to optimize the use of the farm, the GE scheduler pilots the distribution of the jobs in the workers taking into account the resources requirements (memory, running time, accessed storage, etc.) described in the options at submission time. This is why it is important to specify as precisely as possible all the needed resources.
To protect this sharing, it is recommended not to have more than 1000 jobs in queue and to submit a few hundred regularly. Over 3000 jobs, user is blocked for submission and his jobs in queue are deleted.

List of available resources can be found in Informations about Grid Engine complex & RQS (resources) .

Detailed informations on how to use the computing farms through GE and the interactive machines can be found in The Computing Centre batch farm .

Job submission using the GRID

From the interactive machines, you can also use the GRID resources.

To use the GRID, you need to own a valid GRID2-FR certificate and to register to a Virtual Organization (VO). A VO is similar to a UNIX group. Hence you are registered in a VO, the latter will deliver you a proxy , a file signed with your certificate, which allows you to authenticate to access the resources to your VO.

To get more informations, you can consult our web page on GRIDs .

  • en/guide_utilisateur.txt
  • Last modified: 2019/08/02 11:00
  • by David BOUVET