NSSDC's Data Restoration Program Winds Down

Volume 11, Number 1, March 1995
By Sharlene Rhodes and Joseph King
The National Space Science Data Center has a fundamental responsibility to preserve for future access the NASA mission data in its archives. To this end, NSSDC has pursued over the past 6 years a data restoration program in which data were migrated from 35,800 aging tapes to 6,100 pairs of new 9-track tapes and 3,480 tape cartridges. This data restoration program is now concluding in the sense that NSSDC holds no space science tapes older than 10 years, except as noted below.


The data restoration program is being followed by the data preservation activity, which will be a forever-ongoing activity to migrate data to new media when appropriate. Final judgments are being made now to target media for this activity for the next few years, with CD-Write Once and Digital Linear Tape (DLT) being the most likely choices at this time.

Of the 35,800 tapes passed through the data restoration program, approximately 19,800 were space science (astrophysics, space physics, planetary) and 16,000 were Earth science. In general, NSSDC automatically restored all small space science data sets, and enlisted community input in assessing the cost-benefit ratio of restoring large and possibly obsolete data sets. The following data sets were community recommended for non-restoration. These will be deleted after some advertising (including this article):

In addition, NSSDC is able to release an additional 3,000 old space science tapes as holding differently formatted or organized versions of data sets that have been restored for future access, as holding digital planetary image data now being written to CD-Write Once media at the Jet Propulsion Lab, and as holding non-NASA data (mainly geomagnetic) once acquired by NSSDC for the convenience of GSFC scientists.

NSSDC's data restoration program started 6 years ago with a major focus on Earth science (ES) data. About 3 years ago, the NASA ES program, through the Earth Science Data and Information System (ESDIS) Project Office at GSFC, asserted its responsibility for the disposition of the ES data at NSSDC. At this time, NSSDC shifted its data restoration program to space science data. ESDIS, and its associated EOS DAACs, are gradually directing the migration of NSSDC-held ES data to appropriate DAACs. A major review of NSSDC's ES data holdings, coordinated by ESDIS and involving the DAACs and their science teams, was recently completed. ESDIS judgments on the large number of remaining ES datasets are expected to be forthcoming shortly. For any such data set, possibilities are to designate a DAAC (as has been done for the more in-demand of NSSDC's ES data sets already), to migrate to an ES deep archive (likely, NOAA for most data), or to release the data (as for the few space science data sets identified above).

During NSSDC's data restoration program, which operated at an average 4- person staffing level, approximately 98% of the data on the 35,800 tapes addressed were successfully migrated to new media. This includes many tapes received at NSSDC in the 1960s and 1970s, and held in reasonable environmental conditions. In some cases, NSSDC's backup tapes were used when difficulties were encountered in reading the primary tapes.

A variety of computers was used over the life of the data restoration program. ranging from NSSDC's now retired Modcomp Classic, a PC-based system, a micro-VAX system (NSSDCs current Media Replication System), and large IBM mainframes (3081, 9021) operated by Goddard's NASA Center for Computational Sciences. A significant hardware and software challenge was keeping 7-track tape reading capability across these platforms.

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Author:Miranda Beall
Curators: Erin Gardner and Miranda Beall
Responsible Official: Dr. Joseph H. King, Code 633
Last Revised: 04 Dec 1996 [EDG]