[ROOT] chaining/efficiency query

From: Edward Moyse (edward.moyse@cern.ch)
Date: Fri Sep 12 2003 - 14:53:05 MEST


Hi guys,

A quick question: I have 3000 files on castor. At the moment I have a loop 
which chains all the files together, and then the resulting TChain is used 
for the eventloop. This is extremely, extremely slow - so far it's been 30 
mins and only 300 of the 3000 files are chained. 

I'm not sure how ROOT works - does it load the files in memory to chain them? 

Does the number of files make a difference? Would it be quicker to merge the 
3000 into (say) 30 large files and chain those, or is ROOT just limited by 
network performance (i.e. there's nothing I can do)?

Cheers!

Ed Moyse



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