Changing horses in mid-stream (or, how do you follow one of the most successful acts in mass storage?)

The European Centre for Medium-Range Weather Forecasts (ECMWF) has for many years operated a large mass-storage system based on CFS/DataTree. The CFS system will need replacement before the end of the decade, and ECMWF accordingly embarked on a study of available systems which might be suitable. What we found was that, for various reasons, none of the systems available on the market met our needs. Three particular areas stood out in which commercial systems either could not meet our end-of-decade requirement or in which the existing CFS system was already superior. Over the past two years, during our active pursuit of a system that might satisfactorily follow in the footsteps of CFS, we have learned in fact just how good the existing system was. Our initial assumptions that the market would provide, and clearly indicate, an appropriate successor, were quickly proven over-optimistic and we were forced to make the necessary plans to extend the life of CFS. By making common cause with a number of ether sites with a similar background, we were able to indicate more forcibly to the suppliers the direction in which our dissatisfaction lay; although the time scales of the intended installation meant that we were unable to await the delivery of systems with superior specifications, it also meant that we went into a tendering exercise with the knowledge that we might well have to install a noncompliant system that the supplier would undertake to enhance. By the time of the Monterey Symposium, the selected successor system will be only weeks away from acceptance; and we shall be able to present the decisions and plans that have led to the selection of that solution. The remaining tasks will be to commission the system, develop and integrate the necessary services, and to phase over operations from the old CFS system to the new one, which includes the copying of up to 60 terabytes of old data.