SSH

Once you have obtained an ARC account at IRA, you can access the computer cluster nodes from everywhere through host scheduler.ira.inaf.it. Using graphical applications on the cluster is possible through remote X access. The accessible working nodes are listed in the table below. You can enter a node for interactive work by typing:

ssh -X ''<node>''.ira.inaf.it

Useful tip: by typing ‘hostname’ you can know on which node you are

The only nodes accessible to almaf2f accounts are 19 and the 22.

Here you can find some statistics about resources consumption on the arcblXX nodes.

VPN

You need to install OpenVPN (for IRA staff go to https://wiki.ira.inaf.it/index.php/OpenVPN_VPN)

The VPN (Virtual Private Network) allows you to access IRA internal services in a secure and transparent manner. Once connected, you are assigned an address on the private network 192.168.50.x.

Download an OpenVPN client

• Debian GNU/Linux text: openvpn-auth-ldap and openvpn package
• Mac OSX: tunnelblick
• Windows: OpenVPN Guide and  Download

Download the configuration:

• VPN to connect to IRA networks, leaving navigation to other sites unchanged (https://www.ira.inaf.it/vpn/ira-nogw.ovpn)
• VPN for browsing to all sites. Use this configuration only if strictly necessary (https://www.ira.inaf.it/vpn/ira-gw.ovpn)
• VPN for VoIP phone use (https://www.ira.inaf.it/vpn/ira-nogw-tel.ovpn)

Procedure:

• 1 – Start the customer;
• 2 – From the linux command line, as root user:

$ openvpn --config <name_of_the_downloaded_file>

• 3- Provide IRA credentials; the username must be indicated without the domain (@ira.inaf.it)

Please turn off VPN on your computer when not needed.

You need to change the directory to access your ARC storage on the cluster:

cd /iranet/groups/arc/homesarc/''username'' 

Beware that disks have no redundancy at all, never leave important data on them

Mounting ARC storage on you workstation

• On IRA workstations ARC home filesystem can be accessed on /iranet/homesarc
• On your laptop ARC filesystems can be seamlessly accessed with fuse-sshfs:
• as root, install the package sshfs

# on RedHat/Centos/ScientificLinux
yum install fuse-sshfs
# on Debian/Ubuntu
apt-get install sshfs

• then, as user

sshfs storage.alma.inaf.it:/iranet/groups/arc/homesarc/yourhome /your/local/mount/point/

By omitting /remote/path you can mount you home directory.Be aware that this method is suboptimal for heavy input/output loads. Running disk-intensive applications directly on the arc cluster will result in a file access speed 10-50 times faster.

Software packages activation and availability – irainit

Irainit is a script that initializes the execution environment for programs installed in directories (typically exported via NFS). Irainit searches for “inifiles” (files named env.ini) in the subdirectories of the directory set by the $irainit_search_dir environment variable (for example, /iranet/soft). Inifiles are text files in “INI” format.

Initialization

Irainit can be initialized by typing the commands:

irainit load-env is executed, performing the following operations:

• Sources pre-env.sh
• Configures the values it recognizes in the inifile
• Sources post-env.sh
• Sources the execute.sh file

If the package is already loaded, only the execute.sh file is executed.Inside post-env.sh and execute.sh, the following variables can be used:

• PYTHON_VERSION (if present)
• PYTHON3_VERSION (if present)
• version_basedir

At the end of the procedure, the environment variables PATH, LD_LIBRARY_PATH, MANPATH, and PKG_CONFIG_PATH are updated. A SOFTWARE_NAME_DIR variable is also created to reference the software in other scripts.

Other useful irainit functions

$ irainit available

$ irainit display <software>

$ irainit load <software> <version>

Example 1: activating the default version of “casa”:

In this example, we initially activate irainit, then we check the available software, we activate the default version of casapy and finally, we run casa. In this example, we assume the first two commands are not included in the personal .bashrc file and therefore they were not already run at login.

$ export irainit_search_dir=/iranet/soft
$ . $irainit_search_dir/irainit/irainit_setup-alias.sh
$ irainit available
$ irainit load casapy 
$ casa

Example 2: activating a specific version of “casa”:

In this second example, after activating irainit and checking the available software, we also display the available versions of casapy. Then, we activate one specific version of casapy and finally, we run casa. Also in this example, we assume the first two commands are not included in the personal .bashrc file and therefore they were not already run at login.

$ export irainit_search_dir=/iranet/soft
$ . $irainit_search_dir/irainit/irainit_setup-alias.sh
$ irainit available
$ irainit display casapy
$ irainit load casapy 6.1.1-15-pipeline-2020.1.0.40
$ casa

Some of the available packages and software

As said above, software available on the ARC cluster can be listed by typing the command:

$ irainit available

Here below, we report an incomplete list of the available software packages:

Computing Nodes

¹ RAM: [A] AMD Ryzen 7 1800X; [B] Intel Xeon E3-1275 v6; [C] Intel Xeon E5-1650 v4;
² SCH.: Scheduler
³ Group: (a) arc-staff, (b) arc-vlbi, (c) arc-f2f, (d) arc-user; Blades are always dedicated to (a) and (b);

Storage Nodes