IVOA VOSpace Uses iRODS for Distributed Virtual Observatory

The Information Age has transformed how astronomers study the skies. Advanced digital telescopes are providing a bonanza of new information about the universe. To accelerate their science, astronomers have been quick to move toward unifying their many separate digital collections into “virtual observatories.”

By connecting their digital collections, astronomers can carry out seamless comparisons of images of stars, galaxies, and other objects, no matter where in the world the data are stored. And all this information is becoming accessible right from astronomers’ – and the public’s – computer desktops, offering dramatic advances in research and education as it “democratizes” access to scientific resources.

But a virtual observatory cannot operate without a sophisticated data management system to gather, manage, back up, analyze, and share the millions of images and related information. The Data-Intensive Cyber Environments (DICE) group at the University of North Carolina (UNC) and UC San Diego has long collaborated with the US National Virtual Observatory (NVO), and has now extended this work to international partners in the International Virtual Observatory Alliance (IVOA). 

As part of this international alliance, the IVOA is developing VOSpace, a standard interface to a virtual file system that gives access to stored astronomy images and other data distributed across the data collections of multiple participating observatories. To let their VOSpace implementation access multiple types of storage infrastructure on which the diverse astronomical collections reside, researchers at the Astronomical Data Center in Strasbourg, France (Centre de Données Astronomiques de Strasbourg or CDS) are using iRODS, the Integrated Rule-Oriented Data System.

The key to a unified digital observatory is “interoperation” – each participating location being able to talk to all the others. Taking advantage of new technologies, astronomers no longer have to physically assemble their collections in one place – prohibitively expensive and undesirable for other reasons. They can instead create a “virtual observatory” by using a data system than “knows” in its digital catalog where every image is and what its characteristics are, and can help researchers find and bring together in a compatible framework the specific sky images they want, no matter where they are.

The IVOA data are primarily images up to 2 gigabytes in size, along with  XML and text files. After a study of different data management solutions, the French researchers identified the DICE group’s iRODS data system. The astronomy project is now using iRODS underneath a VOSpace interface prototype. The key feature that iRODS gives the VOSpace interface is the capability to manage, move, preserve, and provide access to astronomical data of all types, no matter what local hardware and infrastructure each data collection resides in.

The project is using iRODS in a production installation with 12 terabytes of storage in which iRODS Rules perform an automatic replication of data. The innovative Rules feature of iRODS is important because it makes growth to large data collections feasible by letting astronomers automate labor-intensive data management tasks. The researchers have developed a Java-based VOSpace Explorer interface to access and manage files in iRODS, including support for drag and drop.

The researchers commented that the IRODS system is providing a robust solution for their virtual observatory needs in VOSpace. They noted a number of strengths of the iRODS Data System, including its quick and easy installation, ease of use, flexibility (through user-definable Rules and Micro-services), and extensible architecture. They also found it very useful that iRODS is designed to make it possible to start with a small configuration and then expand as needed.

For technical information and references on the VOSpace application of iRODS see the paper at http://ivoa.net/Documents/latest/VOSpace-iRODS.html.

The researchers are presenting their work in the iRODS workshop at the Institut National de Physique Nucléaire et de Physique des Particules (IN2P3) in Lyons, France in February, 2009.

iRODS is supported by the National Science Foundation and the National Archives and Records Administration. For more information see http://diceresearch.org. --by Paul Tooby

Related links

•IVOA paper on VOSpace http://ivoa.net/Documents/latest/VOSpace-iRODS.html

•iRODS Workshop http://www.diceresearch.org/DICE_Site/Home/Entries/2008/10/13_Learning_About_IRODS%3A_Workshop_Registration_Opens.html

•International Virtual Observatory Alliance (IVOA) http://ivoa.net/

•Euro-VO VOtech Project http://eurovotech.org

•   Data Intensive Environments (DICE) Group http://diceresearch.org

•Integrated Rule-Oriented Data System (iRODS) https://www.irods.org/

Aladin is a Virtual Observatory portal that gives astronomers and others easy access to images in VOSpace using iRODS to access to data from multiple distributed collections. Developed by researchers at the Astronomical Data Center in Strasbourg, France (Centre de Données Astronomiques de Strasbourg or CDS).

iRODS helps the IVOA-compliant VOSpace virtual observatory interface access astronomical images and data independently of the infrastructure they are on or where they are located.