CMSSW Fallback

The patch attached to this page allows a CMSSW run to fallback from the normal TFC access to a secondary protocol, such as the global xrootd redirector.

This is only tested on CMSSW_3_8_0 or later.

CMSSW Patches

Before you apply any patches, make sure you have your CMS environment set up correctly. From the CMSSW_3_8_x directory, do:

cmsenv
export CVSROOT=:pserver:anonymous@cmscvs.cern.ch:/cvs_server/repositories/CMSSW

Now, apply patches and build the new code:

addpkg IOPool/Input
addpkg FWCore/Services
addpkg FWCore/Catalog
pushd src/FWCore/Catalog
/usr/bin/curl -k https://twiki.cern.ch/twiki/pub/Main/CmsIOFallback/fwcore_catalog_fallback.patch | patch -p0
popd
pushd src/FWCore/Services
/usr/bin/curl -k https://twiki.cern.ch/twiki/pub/Main/CmsIOFallback/fwcore_services_fallback.patch | patch -p0
popd
pushd src/IOPool/Input
/usr/bin/curl -k https://twiki.cern.ch/twiki/pub/Main/CmsIOFallback/iopool_input_fallback.patch | patch -p0
popd
scram b -j4 USER_CXXFLAGS="-g"

Add the xrootd service to the CMSSW run

    <event-data>
      <catalog url="trivialcatalog_file://opt/osg/app/cmssoft/cms/SITECONF/local/PhEDEx/storage.xml?protocol=direct"/>
    </event-data>

    <event-data>
      <catalog url="trivialcatalog_file://opt/osg/app/cmssoft/cms/SITECONF/local/PhEDEx/storage.xml?protocol=direct"/>
      <catalog url="trivialcatalog_file://opt/osg/app/cmssoft/cms/SITECONF/local/PhEDEx/storage.xml?protocol=xrootd"/>
    </event-data>

where the xrootd protocol points to the xrootd redirector of your choice. If you want to use the global redirector, you would add the following line to your storage.xml file:

  <lfn-to-pfn protocol="xrootd" destination-match=".*" path-match="/+store/(.*)" result="root://xrootd.unl.edu//store/$1"/>

You can run CMSSW as normal; whenever CMSSW runs into a file it can't open, it will start using the CMS Data Access Testbed.