The ARC cluster

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The ARC is equipped with a dedicated computer server connected with a high-speed optical fiber network to the outside world, allowing fast data transfer (1 Gbit/sec in 2009; 10 Gbit/sec by 2012). Presently we have 77 Tb of diskspace and one 12-unit blade cluster (96 cores) dedicated to the ARC.

ALMA and CASA users can request access to the server and the disk space by sending an e-mail to arc-support at indicating the reason for the request.


User policy

New ARC users can access the Italian ARC node computing facilities by requesting a face-2-face visit (ALMA users only, through the ALMA Helpdesk) or by visiting the ARC node in Bologna (for any data-reduction-related issue to be solved in collaboration with the ARC staff). In both the cases they are requested to send an e-mail to indicating the reason for the request.

Please notice that the request for a new account for a new requesting user implies that he/she (and/or his/her collaborators) visit the ARC for an induction on the ARC facilities usage and on issues related to data reduction with CASA both for ALMA and any other telescope. If the request is positively evaluated the visit details will be arranged via e-mail.

The account will guarantee the usage of the facilities and the support for 6 months. Every user can use 1 TB of disk space. Once the account expires the access to the data will be suspended and, after 1 month of quarantine ALL DATA WILL BE REMOVED. No reminder of the deadlines will be sent. Extensions of the account duration period could be considered on request (via e-mail). No visit is needed in case of account renewal.

The ARC members support is guaranteed for any ALMA-related issue. For data-reduction-related issues that do not involve ALMA, the support (other than the technical support in the usage of the ARC computing facilities) is limited to the knowledge/experience and availability of the ARC members.

Upon explicit request IRA staff people can have an account with unlimited duration. IRA collaborators with temporary positions can have an account for the entire duration of their position.

To ensure a well-balanced load on the cluster nodes please follow instructions about accessing the computer cluster

Queries can be issued via e-mail to

Private:Cluster Accounts

Accessing the computer cluster

Once you have obtained an ARC account at IRA, you can access the computer cluster nodes from everywhere through host Using graphical applications on the cluster is possible through remote X access. The accessible working nodes are listed in the table below. Never submit workloads to arcserv (control node) and arcnas1 (storage) as this can slow down the entire cluster. You can enter a node for interactive work by typing:

ssh -tX

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

Access is done via a Torque/Maui scheduler that redirects your job on the less-loaded node.

Jobs on the cluster are limited to a duration of 168 hours.

Here you can monitor the status of Torque scheduler and the number of active jobs.

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

Executing programs

You can execute programs in two ways:

in interactive mode - your command is immediately executed on the less-loaded node and standard input, output and error are linked to your terminal.

or scheduling a pbs job - submit a job file (here is a guide)

Copying files to from the ARC storage

You can put and get files from outside with scp on the cluster via

# from storage...
scp /local/path
# and to storage
scp /local/path

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 /your/local/mount/point/

By omitting /remote/path you can mount you home directory. i.e.:

sshfs /your/local/mount/point/

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 available

Software available on ARC cluster could be listed typing the command setup-help

Software package setup command launch command notes
CASA casapy-setup casapy data reduction package
Miriad miriad-setup miriad data reduction package
aips aips-setup
analysis utils analysisUtils-setup
analytic infall analytic_infall-setup
astron astron-setup
Coyote library coyote-setup
fits Viewer fv-setup
GCC Compiler gcc-setup
Gildas gildas-setup
Healpix healpix-setup
IDL idl-setup
heasoft heasoft-setup
QA2 qa2-setup
Ratran ratran-setup
Starlink starlink-setup


name ram cores scheduler speed notes
arcbl01 32G 16 N 3500
arcbl02 8G 8 Y 2100
arcbl03 8G 8 Y 2100
arcbl04 8G 8 Y 2100
arcbl05 8G 8 Y 2100
arcbl06 8G 8 Y 2100
arcbl07 8G 8 Y 2100
arcbl08 8G 8 N 2100
arcbl09 8G 8 N 2100
arcbl10 32G 16 N 3500
arcbl11 8G 8 N 2100
arcbl12 16G 8 N 2100
arcbl13 16G 4 N 2800