TFile problems / Max TFile size?

Hi everybody,

I’m trying to merge several root files to one big file where some cuts have already been applied. Therefore I’m creating a TChain containing the root files. Then I’m copying this chain with

TTree *cuttedcopy = chain->CopyTree(myCuts);

Afterwards I’m opening a file and want to write the created tree to this file with

TFile *out = new TFile(filename, "RECREATE");

Now I get different behaviours. If I just add a single file to the chain everything works perfect. But if I try to add more files to the chain I reach a point where things are getting strange. If I specify the file name as relative path, e.g. “cutted.root” I get the error

SysError in TFile::TFile: file cutted.root can not be opened (Permission denied)

This worked with the single file so I should have write privileges. Now if I specify the file name as absolute path, e.g. “/home/mathias/cutted.root” I just get the error that the operation was aborted.

Any ideas on that? Is there perhaps a limitation on the size of root-files? The final size of the file to be written on disk should be something like 250 MB which is not so much. I thought root could handle this. At least there should be no problems with my SuSE 9.3 and ReiserFS to handle these filesizes.

Thx for any hint,


You should create the output file before Copytree


Thanks, that works perfectly!