In order to create a hierarchical and secure archive for their dozens of terabytes of image and cartographic data, the IGN has chosen a solution from the software vendor Active Circle.

The IGN and the SIEL

The On-Line Information Service (SIEL) is responsible for archiving all the cartographic data produced by the IGN.  Additionally, the Service is also in charge of managing the images available via their website Geoportail (http://www.geoportail.fr).  This involves the management of two different types of data: vector images for the maps and raster images stored in TIFF and ECW (Enhanced Compression Wavelet) formats.  “The production teams at the IGN send us their data in SIP (Submission Information Package) format, which includes images that have already been compressed in TAR format and the associated metadata.  Obviously, the data streams are much larger for the raster images,” notes Yann Le Disez, manager of the distribution and archiving department at the SIEL.

Previously this IGN department employed the Dorostore system in conjunction with an electronic catalog supported externally, resulting in very long archiving times.  In 2007, in order to confront the extraordinary growth of data to archive (50 Tb through 2007 with an additional 25 Tb estimated at the time for 2008), the SIEL decided to completely re-engineer the system, opting for a unified, secure, and scalable archiving solution on LTO tape.  An invitation to tender was announced and four system integrators responded.

Requirements: adapting to best practices

In the end, it was the solution proposed by the system integrator Komposite that won out over the three others.  For the SIEL, it was the one best adapted to the specific developments already implemented.  “In conformity with the procedures of a European open invitation to tender, we had defined three criteria for selection: technology, price, and delivery schedule.  One very well-known integrator proposed a system with all the required elements, but which we had to reject because we wanted an open tool capable of integrating with the elements of our existing workflow,” explained Yann Le Disez.

The department archives its data according to well-defined procedures using the Open Archival Information System (OAIS) conceptual model.  This process requires that before creating any archive they must generate the previously mentioned SIPs, which are based on an open compression standard, rather than relying on the compression functionality and capabilities of a proprietary archiving system.  This operation is in fact carried out in the individual production departments using a program  developed in-house.

Architecture: A Fault-Tolerant System

Two high-performance NAS units from Exanet host the cartographic data that can be accessed from the site according to well-defined hierarchical rules (retention times differ according to the content).  They also serve as a buffer for the final archiving to LTO4 cartridges in the NEO 8000 tape library located at the IGN's Saint-Mandé site outside of Paris.