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You can run fireworks (cmsShow) on your laptop or desktop machine and access data directly from our Tier-2 dCache.
Just put the prefix 'root://dcache-00.rcac.purdue.edu/pnfs/rcac.purdue.edu/data/' in front of the LFN.

Example:
{code:xml}
> cmsShow root://dcache-00.rcac.purdue.edu/pnfs/rcac.purdue.edu/data/store/data/BeamCommissioning09/MinimumBias/RAW-RECO/SD_AllMinBias-Jan23Skim-v1/0014/AC5CE429-B809-DF11-85F1-0026189438A9.root
{code}

To copy a single file from the Tier-2 dCache to your local machine (laptop or desktop) you can use the command *xrdcp*.
First you need to initialize your ROOT or CMSSW environment (run cmsenv).

Example:
{code:xml}
> xrdcp root://xrootd.rcac.purdue.edu//store/group/ewk/DY/DYM20/ntuple_skim_96_2_z5w.root my.root
{code}

You will get a progress bar as the file downloads. You may also want to think about using the \-R option, which allows you to recursively download a directory.
Please see the details at [https://twiki.opensciencegrid.org/bin/view/Tier3/XrootdClient]

If you are using ROOT, you can open files from our Tier-2 dCache just like you would any other file:
{code:xml}
TFile::Open("root://dcache-00.rcac.purdue.edu/pnfs/rcac.purdue.edu/data/store/data/BeamCommissioning09/MinimumBias/RAW-RECO/SD_AllMinBias-Jan23Skim-v1/0014/AC5CE429-B809-DF11-85F1-0026189438A9.root");
{code}
This returns a TFile object, and you can proceed normally.

 
h2.Data access through AAA:

Check for file availability with:
{code:xml}
> xrd cms-xrd-global.cern.ch existfile /store/myfile.root 
{code}
Direct access: ROOT and CMSSW PoolSource can open a remote file directly through AAA 
{code:xml}
> “root://cms-xrd-global.cern.ch//store/myfile.root” 
{code}
Make a local copy:
{code:xml}
> xrdcp root://cms-xrd-global.cern.ch//store/myfile.root /localpath/myfile.root 
{code}
For additional information see: [https://twiki.cern.ch/twiki/bin/view/CMSPublic/WorkBookXrootdService]