Dear root users, i have a question concerning large data volumes. At H1 our data is split in approx 200 MB files which are stored on tape and can be retrieved via fpack. Is it possible to do it in a similar way in root ? Of course it would be possible to write N events to a files, so that the files has an approximate size of 200 MB, but if i want to plot one variable i would have to copy each file from tape (which is the slowest step) and add up the distributions calculated for each file. It would be more clever, if one would have one branch of the TTree in one file, so that i would have to stage one file only (and maybe the files containing the tree structure). Is there a way in root to make this automatically ? (i.e. opening a TFile with a TTree containing several branches results in serveral files, each of them containing only a few branches ?) Ciao Thomas ---------------------------------------------------------------------------- Thomas Hadig, Ottensen, Donnerstr. 20, D-22763 Hamburg (++49 40 39901186) office : I. Phys. Institut AAC, Room 1c354, Notkestr. 85, D-22603 Hamburg hadig@rwth-aachen.de Tel. ++49 40 8998 2312 http://www-h1.desy.de/~hadig/ FAX ++49 40 8998 4385 ---------------------------------------------------------------------------- In a world without walls and fences, who needs windows and gates ? ----------------------------------------------------------------------------
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