1.3 The ARC middleware

In grid computing users don't log in directly to the computing clusters they are using. Instead, the computing tasks are submitted via a job broker tool called middleware. FGCI uses the ARC (Advanced Resource Connector) middleware, developed by the Nordugrid community. There are also several other commonly used grid middlewares like gLite and Unicore. Currently it is not possible to use these middleware packages with FGCI.

The ARC middleware consists of two parts, the ARC server, which runs in the computing servers of FGCI, and the ARC client, that is used to send computing tasks to the ARC servers. To send jobs to the FGCI you must either install the ARC client to your local computer or use the ARC client available at CSC on Taito (taito.csc.fi).

1.3.1 Using the ARC client at CSC

To be able to use the ARC client on Taito (taito.csc.fi) you must create a sub-directory called .globus in your CSC home directory (note that the first character of the directory name is a dot) and copy your usecert.pem and userkey.pem certificate files to this directory.

You can copy the files from your own computer with, for example, the scp command or you can use the My Certificates tool of the Scientist User Interface (see chapter 1.1.4). Note also that the access permissions of the userkey.pem file should be set up with command:

chmod 400 ~/.globus/userkey.pem

Once the certificate and client-conf files are correctly installed, you can execute ARC commands as discussed in section 2 of this guide.

 

1.3.2 Installing the ARC client to a local computer

The ARC middleware client can be installed on Linux, Mac and Windows machines. There are several alternative ways to do the installation. In many Linux distributions, you can install the repository version of the clients using tools like yum or apt. This allows you to always use the latest release of the client. More information about the repository installation can be found from the ARC repository page:

http://download.nordugrid.org/

The repository installation requires that you have administrator privileges for your computer (root or sudo access). If you don't have administrator privileges, you can obtain a pre-compiled version of ARC from the address:

http://download.nordugrid.org/standalone.html

At this URL , first select the correct operating system, version and processor architecture and press Download. For Linux systems the installation data set is a packed file that can be unpacked with the command:

tar zxvf installation_file

For example:

tar zxvf nordugrid-arc-standalone-11.05-2.el6.x86_64.tgz

The unpacked installation directory includes pre-compiled ARC commands and two set-up scripts: setup.sh for bash and sh command shells and setup.csh for csh and tcsh command shells. Whenever you log into your system and wish to start using ARC commands, you must first go to the ARC installation directory and execute one of these setup scripts (depending on the command shell you are using). For example, in the case of bash command shell:

cd nordugrid-arc-standalone-11.05-2
source setup.sh
Alternatively, you can set this into your login script. Simply add following lines to your .bashrc file:
location=`pwd`
cd /path/to/arc_installation/nordugrid-arc-standalone-11.05-2
source setup.sh
cd $location

 

1.3.3 ARC settings on your local computer

In addition to the ARC client installation you must make sure that a valid grid certificate is available in your .globus directory that is located in your home directory (see chapter 1.1.4. ). You can easily check that by running command: ls -l ~/.globus

The file listing, printed by the command above, should include the files usercert.pem and userkey.pem. In addition to the certificates you will also need an ARC configuration file called client.conf. This file defines a set of parameters that are needed to use the FGI clusters. The file can be downloaded from CSC and it should be placed into a sub-directory of your home directory called .arc (note: the dot is the first character of the directory name). You can do the installation with the commands:

cd ~
mkdir .arc
cd .arc
wget https://confluence.csc.fi/download/attachments/13013454/client.conf

 

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