1. Status of OPAL data Matthias Schröder (Matthias.Schroder@cern.ch)Matthias.Schroder@cern.ch

2. About OPAL OPAL: The Omni Purpose Apparatus at LEP See OPAL Page for Particle PhysicistsOPAL Page for Particle Physicists Data taking from 1989 - 2000 27-Jan-2009Status of OPAL data2

3. Data Types Raw Data – RAWD Data Summary Tapes – DDST, DST, CSDST File sizes: < 200 MB With very few exceptions (N-tuples) – No central management 27-Jan-20093Status of OPAL data

4. Raw Data Packed hit-level information In ZEBRA format Stored on tape – Maintained (copy to new media) by CERN/IT One copy on magneto-optical disks – Medium very good for archiving – Drives and cataloging an issue 27-Jan-20094Status of OPAL data

5. Data Summary Tapes Reconstructed tracks, clusters, event shape,… – Compressed Results of event selections In ZEBRA format – Event header for analysis pre-selection – No streaming, but direct access lists Subtypes – DDST: Hit info kept for all event types – CSDST: Hit info kept for some event types This is what users read for the analysis On tape (castor) – Intermixed with other users data 27-Jan-20095Status of OPAL data

6. OPAL Software F77 based Source in patchy – On purpose Heavily relying on CERNLIB – ZEBRA – Patchy – HBOOK/PAW Stored in afs – Copy in pubarch 27-Jan-20096Status of OPAL data

7. Monte Carlo Several Generators used – Output 4-vectors stored (in weird format) on tape GEANT3 for detector simulation Production system – Input 4-vectors, output reconstr. DDST Frequently used samples: another step makes CSDST – Made heavy use of fatmen – Not working anymore 27-Jan-20097Status of OPAL data

8. Data Preservation Objectives Allow to continue analysis activities Combined analyses with other experiments Check new results or models – Does require ability to produce MC Open Acces not foreseen – Knowledge of strenghts and weaknesses required – All future analysis accompanied by LTEB member 27-Jan-20098Status of OPAL data

9. Data Preservation Data: count on CERN/IT for tape migration – Preserve 4-vectors, RAWD, DDST, CSDST – Should have a second copy elsewhere – Catalog: shall we rely on castor only? No central effort to preserve Ntuples Software: try to keep alive – Migrate to new OS versions – Migrate to changing environments (castor2) – But rely on CERNLIB And availability of 32 bit compilers 27-Jan-20099Status of OPAL data

10. Data Preservation, ctd. Documentation – OPAL primer – Technical Notes – Wiki for documenting changes Just started Expertise – Long Term Editorial Board (LTEB) Experts from sub-detectors, computing, analysis WGs 27-Jan-200910Status of OPAL data

11. Issues Data losses – Tapes do wear out Effects all types of data Technology changes – Compilers – Cernlib – Tape access – Catalog 27-Jan-200911Status of OPAL data

12. Issues, ctd. Loss of software – Most analysis jobs stored in private directory – Problem with commercial software No more visualisation – No CERNLIB build for SL5 foreseen Loss of documentation – Private notes not collected centrally Loss of expertise – People retire, go to industry – People forget Accounts get deleted – Not every detail is documented Why write down the obvious… 27-Jan-200912Status of OPAL data

13. Issues, ctd Resources – No more budgets – No more staff 27-Jan-2009Status of OPAL data13

14. Conclusion Started (too?) late Efforts to improve documentation (So far) manage to keep data alive Worries – Future of CERNLIB – Tapes wearing out – Fading memories 27-Jan-2009Status of OPAL data14