DcacheTestDescriptions < LCGTier2

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---+!! Test descriptions for the dCache tests

%TOC%

Attached to this page you will find a small script which tests the different protocols [[%ATTACHURL%/test-dCacheProtocols.sh][test-dCacheProtocols.sh]].
This is mainly intended for a fast check of the basic functionality, i.e. typically after any kind of change to the system or a service restart. 

---++ gsidcap

---+++ command line =dccp= client
*gsidcap* and a valid proxy certificate allows writing to and reading from the dCache
<verbatim>
dccp /tmp/mytesttree.dat gsidcap://storage01-lcg.projects.cscs.ch:22128/pnfs/projects.cscs.ch/cms/local_tests/mytesttree.dat
dccp gsidcap://storage01-lcg.projects.cscs.ch:22128/pnfs/projects.cscs.ch/cms/local_tests/mytesttree.dat /tmp/somefile
</verbatim>

---+++ access from ROOT %ICON{choice-no}% 
This did not work. Maybe some kind of library mismatch. However I have seen no usage of this protocol from other CMS installations, so we ignore it for the moment.

---++ dcap
dcap only allows reading of files (insecure protocol).

---+++ command line =dccp= client
<verbatim>
dccp dcap://storage01-lcg.projects.cscs.ch:22125/pnfs/projects.cscs.ch/cms/local_tests/mytesttree.dat /tmp/somefile
</verbatim>

---+++ access from ROOT

Set up the ROOT environment as outlined [[#HowToRootTree][below]] and start ROOT. Then on the ROOT prompt:
<verbatim>
root [0] TFile *f1=TFile::Open("dcap://storage01-lcg.projects.cscs.ch:22125//pnfs/projects.cscs.ch/cms/local_tests/mytesttree.dat");

root [1] .ls
TDCacheFile**           dcap://storage01-lcg.projects.cscs.ch:22125//pnfs/projects.cscs.ch/cms/local_tests/mytesttree.dat
 TDCacheFile*           dcap://storage01-lcg.projects.cscs.ch:22125//pnfs/projects.cscs.ch/cms/local_tests/mytesttree.dat
  KEY: TTree    t1;1    simple gas example

root [2] f1->Print();
TFile: name=dcap://storage01-lcg.projects.cscs.ch:22125//pnfs/projects.cscs.ch/cms/local_tests/mytesttree.dat, title=, option=READ
</verbatim>

Draw an example histogram:
<verbatim>
root [3] t1->Draw("px");
</verbatim>


---++ xrootd

---+++ using command line =xrdcp= client
Set up the ROOT environment as outlined [[#HowToRootTree][below]]. 

$> xrdcp -d 3 root://storage01-lcg.projects.cscs.ch:1094//pnfs/projects.cscs.ch/cms/local_tests/derek_dccp1.dat /tmp/gaga

---+++ access from ROOT

Since xrootd speaks ROOT's native protocol, you can directly use URLs like in the xrdcp example above with ROOT's IO directives.


---++ How to produce a ROOT test tree
#HowToRootTree

To test reading files with ROOT you should produce first some ROOT files containing trees.

   1. Get the [[%ATTACHURL%/testtree.C][testtree.C]] file which is attached to this page and save it to your local directory
   1. Set up the environment for ROOT (I'm using here a version from the CMS SW area)
   <verbatim>
export ROOTSYS=/experiment-software/cms/slc3_ia32_gcc323/lcg/root/5.13.04e/root
export PATH=$PATH:$ROOTSYS/bin
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$ROOTSYS/lib
   </verbatim>
   1. Start root
   <verbatim>
$ root -l
   </verbatim>
   1. At the root prompt execute the following commands (this compiles =testtree.C=)
   <verbatim>
root [0] .L testtree.C++
Info in <TUnixSystem::ACLiC>: creating shared library /home/dfeich/roottest/./testtree_C.so
   </verbatim>
   1. Now you can generate test trees using invocations like the following (where =n= is the amount of records to put in the tree)
   <verbatim>
root [1] write_testree(10000,"/tmp/mytesttree.dat")
   </verbatim>
   1. Quit root (for the uninitiated)
   <verbatim>
root [1] .q
   </verbatim>
   1. Copy the file to the dCache using *gsidcap* or *SRM* protocol (I was not able to directly _write_ do dCache with *dcap*. The *xrootd* interface to dCache also seems to share this limitation, so these protocols are ok for reading only)


-- Main.DerekFeichtinger - 16 May 2007

Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who	Comment
sh	test-dCacheProtocols.sh	r2 r1	manage	1.7 K	2007-05-16 - 07:41	DerekFeichtinger	little test script to check protocols
C	testtree.C	r1	manage	0.8 K	2007-03-19 - 15:15	DerekFeichtinger