1. Scientific Computing Division NCAR/CISL/SCD User Forum Using the Mass Store Subsystem Efficiently May 19, 2005 Mike Page Consulting Services Group mpage@ucar.edu

2. Scientific Computing Division Efficient Usage NCAR\ Users CISL \ SCD

3. Scientific Computing Division NCAR Mass Store Subsystem (MSS) Currently stores two petabytes of data Library of Congress (printed collection) 10 Terabytes Mass Store holds 200 * Library of Congress Data holdings increasing exponentially 1986 - 2 Tb 1997 - 100 Tb 2002 - 1000 Tb 2004 - 2000 Tb

4. Scientific Computing Division NCAR Mass Store Subsystem Capacity vs. Demand Planning, planning, planning CSG/MSSG assistance available Is it a file server? Recommended file sizes Recommended volume of metadata operations Other keys to efficient usage Be selective in the data stored on the MSS Avoid repetitive reads/writes Choose class of service and retention periods according to value of data

5. Scientific Computing Division

6. If: – you are no longer active on any project – your project closes – you are no longer employed by UCAR/NCAR – you are doing periodic maintenance of your MSS files You can: – delete your MSS files yourself – request that the SCD delete your files – change the project number to an active account – transfer ownership of the files to another user – transfer the data between the MSS and other media – 1 Terabyte > 300 DVDs – transfer data to another network location File purge policies

7. Scientific Computing Division How to access information on your MSS holdings http://www.scd.ucar.edu/docs/mss/MSSholdings.html

8. Scientific Computing Division MSS Summary Report

9. Scientific Computing Division Summaries

10. Scientific Computing Division Class of Service

11. Scientific Computing Division Mass Store Access from Command Line and Batch Scripts

12. Scientific Computing Division MSS Access from User Applications f90 -L /usr/local/lib -l mss test.f msread - retrieve file from mass store and make it local mswrite - write local file to mass store msrecall - wait for specific async read/write to complete mswait - check status of all queued async reads/writes to complete mserror - get error messages for last failed read/write

13. Scientific Computing Division The End