[Halld-offline] Hall-D Computing plan and storage of simulated data.

[David Lawrence]

Hi All,

Just a follow up to the discussion at the meeting on Wednesday. I'd 
mentioned that Mark had submitted the document I wrote up in 2008 when 
filling out Chip's original spreadsheet. The document titled "12GeV 
Computing Plan" is GlueX-doc-1431. As to the specific issue of storing 
simulated data, it has this in the second paragraph on page 2:

"Hall-D currently plans to follow a computing model that stores very 
little simulated data on tape. The expectation is that it would be 
nearly as fast or faster to reproduce the data as it would be to read it 
off of tape and reprocess it. The “DST” files produced by the simulation 
are therefore only expected to need 10% of the disk space used for the 
raw, simulated data that will exist only on the farm nodes."

This was not backed up by any hard numbers but I still suspect it is 
true. This refers only to what is needed regarding JLab resources and 
not what may be implemented outside of JLab (and JLab's budget). To my 
knowledge this represents what is our current Computing Plan for Hall-D.

Regards,
-David