Keywords: DataAccWG Hi,
I published in docushare the updated spreadsheet with Database Size Estimates.
https://www.lsstcorp.org/docushare/dsweb/Get/Document-1779/lsst_storage_estimates_v10.xls It is based on assumptions that we have one big Object table (galaxies + stars) in deep db, and measurements for galaxies per frame in time db. The numbers are somewhat bigger than we expected: we are talking about 400 TB of pure data (no overheads) in the first year now, comparing to 70 TB before (Ouch!) I tried to understand why the change is so big. Here it is: DEEP DB: 3.09 --> 11.7 TB. Why? - we used to have row size 180 bytes (stars) & 880 bytes (galaxies) Now row size of the Object table is 1.8KB. The fact that there there are more stars than galaxies (4:3) in DR1 makes things worse. - Why is the row size so much bigger? We have to carry information for each filter (basically roughly what we had: 180 bytes x 6 filters), plus discussed 50% for reserved space TIME DB: 19.1 --> 121 TB. Why? 1) we used to have row size = 70, now it is 306 2) We added sources for galaxies (ratio galaxy:stars in time db is 0.45). So that is 19.1 * 306/70 * 0.45 = 121 - Why did the row size change so much? We were previously guessing we will need ~70 bytes for attributes related to stars in temp db. Now we are assuming size of Source row (204 bytes), plus +50% reserved space, gives 306 Jacek _______________________________________________ LSST-data mailing list [email protected] http://www.lsstmail.org/mailman/listinfo/lsst-data
