Volume 15, Number 3, September 1999
By Joseph King and Robert Candey
For nearly a decade now, NSSDC has provided astrophysics and space physics data files from NDADS, a VMS system with a pair of Cygnet jukeboxes holding 12" optical platters with a combined capacity of about 1.6 TB. Over that time more than two million data files have been downloaded by NSSDC's customers. User response times have typically been in the few-to-several minutes range.
The optical disk jukeboxes are approaching the end of their useful lives. NSSDC has just taken delivery of a 1 TB RAID magnetic disk system from MetaStor, which has been attached to a SUN Enterprise 3000 server running UNIX. NSSDC expects that in the coming several months most space physics data on NDADS and the still popular data from the Infrared Astronomy
Spacecraft (IRAS) will be migrated from Cygnet platters to the new RAID-based NSSDC Data Management System (NDMS).
Initially, NDMS user access will be by anonymous/FTP through a directory hierarchy largely organized by spacecraft and experiment. After the data transition is completed and all new ingests are pointed to the RAID disk rather than to the Cygnets, the old NDADS service and its SPyCAT, WISARD, and ARMS interfaces will be abandoned.
NSSDC expects to integrate into this new NDMS the spacecraft data files that have long been accessible from NSSDC via an anonymous/FTP pathway completely independent of the NDADS pathways. Whether NSSDC eventually creates higher level interfaces to these data files will depend on user feedback.
This change will not affect such popular data access pathways as CDAWeb and OMNIWeb. A key reason for needing less immediate capacity than the prior Cygnet-based NDADS system is that new electronic pathways outside NSSDC are now available to high energy (HEASARC) and UV (STScI/MAST) astrophysics data that previously were uniquely available from NDADS.
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