How To Get Data From Dcache directly by Root

when using Root, you can specify the root files in 2 different ways:

1 download these files from the dcache directory,then specify the file as a local one. As follows:

1) download the file from dcache using dccp

root@umt3int03 /data02/home/aww/root-5.14-amd64/tutorials#

dccp dcap://head01.aglt2.org/pnfs/aglt2.org/dq2/trigg_misalg_csc11/AOD/trigg_misalg_csc11.005300.PythiaH130zz4l.recon.AOD.v12000601_tid007179/trigg_misalg_csc11.005300.PythiaH130zz4l.recon.AOD.v12000601_tid007179._00160.pool.root.1 .

61496112 bytes in 2 seconds (30027.40 KB/sec)

2) Insert this file to the file list you are using..

h101.Add("trigg_misalg_csc11.005300.PythiaH130zz4l.recon.AOD.v12000601_tid007179._00160.pool.root.1");

3) run Root .

ps: also there are several ways you can download a file from dcache. you can use srmcp or globus-url-copy instead of dccp. For more information about this,see

* HowToAccessDcacheDataFromLocal

2 Get files directly from dcache. You just need to replace the original files with the new dcap file path. As follows:

chain->Add("dcap://head01.aglt2.org/pnfs/aglt2.org/dq2/trigg_misalg_csc11/AOD/trigg_misalg_csc11.005300.PythiaH130zz4l.recon.AOD.v12000601_tid007179/trigg_misalg_csc11.005300.PythiaH130zz4l.recon.AOD.v12000601_tid007179._00160.pool.root.1");

......

notice: you can use any other nodes which have dcap door installed instead of head01.aglt2.org..

refer to http://head01.aglt2.org:2288/cellInfo for more dcap door nodes..

you can do this wherever you need to specify the path of the file you want to use in Root .

-- WenjingWu - 11 Sep 2007