(r3) CmsIOFallback < Main

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---+ 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:
<verbatim>
cmsenv
export CVSROOT=:pserver:anonymous@cmscvs.cern.ch:/cvs_server/repositories/CMSSW
</verbatim>

Now, apply patches and build the new code:
<verbatim>
addpkg IOPool/Input
addpkg IOPool/TFileAdaptor
addpkg FWCore/Sources
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"
</verbatim>
It might take 3-5 minutes depending on the speed of your computer.

---++ Add the xrootd service to the CMSSW run
Assuming that your site-local-config.xml event-data stanza looks like this:
<verbatim>
    <event-data>
      <catalog url="trivialcatalog_file://opt/osg/app/cmssoft/cms/SITECONF/local/PhEDEx/storage.xml?protocol=direct"/>
    </event-data>
</verbatim>
change it to the following:
<verbatim>
    <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>
</verbatim>

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

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.

Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who
patch	fwcore_catalog_fallback.patch	r2 r1	manage	8.0 K	2010-07-13 - 21:30	BrianBockelman
patch	fwcore_services_fallback.patch	r1	manage	2.5 K	2010-07-13 - 04:59	BrianBockelman
patch	iopool_input_fallback.patch	r1	manage	2.2 K	2010-07-13 - 05:00	BrianBockelman

Topic revision: r3 - 2010-07-13 - BrianBockelman

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