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Hi Pablo,

The xroot protocol does not allow you to rewrite the filename. This was 
specifically asked for by previous experiments. The way people handle it is 
a) create a Name2Name plugin that rewrites the name (new versions of dCache 
have this) or b) run a proxy service that rewrites the name. We are 
exploring future possibilities but, for now, those are the options.

Andy

-----Original Message----- 
From: Pablo Fernandez
Sent: Wednesday, February 27, 2013 6:49 AM
To: [log in to unmask]
Subject: xrootd.redirect changing the namespace

Dear all,

I have a question, related to the CMS xrootd Federation that is
currently being established.
We currently have an storage element (dcache) with a normal
authenticated xrootd door (storage01), and files inside the CMS
namespace are named this way:
/pnfs/lcg.cscs.ch/cms/trivcat/this/is/my/file

And we have installed an xrootd redirector in another host (not inside
the dcache cluster) as specified here:
https://twiki.cern.ch/twiki/bin/view/Main/CmsXrootdArchitecture
And this redirector is called cmsvobox.

That host registers files into a xrootd manager, striping out the site
location from the filename, so files look like /this/is/my/file. And the
idea is that an external client can then connect to our redirector and
ask for:
   cmsvobox:/this/is/my/file
And that should be redirected to our xrootd dcache door (storage01) to
the file:
   storage01:/pnfs/lcg.cscs.ch/cms/trivcat/this/is/my/file

Redirect works, but we can't make it so that cmsvobox redirects *and
adds* the missing part of the filename.

cmsvobox xrootd relevant config looks like this:

all.manager xrootd.ba.infn.it:1213
oss.localroot /pnfs/lcg.cscs.ch/cms/trivcat
xrootd.redirect storage01.lcg.cscs.ch:1094 /
all.export / nostage readonly
oss.namelib /usr/lib64/libXrdCmsTfc.so
file:/etc/xrootd/storage.xml?protocol=direct


And the relevant part of storage.xml:
  <lfn-to-pfn protocol="direct" destination-match=".*"

path-match="/+store/PhEDEx_LoadTest07/LoadTest07_[^/]+_CSCS/[^/]+/[^/]+/(.*)_.*_.*"

result="/pnfs/lcg.cscs.ch/cms/trivcat/store/phedex_monarctest/monarctest_CSCS-DISK1/$1"/>

  <lfn-to-pfn protocol="direct" destination-match=".*"
    path-match="/+(.*)" result="/pnfs/lcg.cscs.ch/cms/trivcat/$1"/>

  <pfn-to-lfn protocol="direct" destination-match=".*"
    path-match="/pnfs/lcg.cscs.ch/cms/trivcat/(.*)" result="/$1"/>


I have to admit I am not an xrootd expert, so any help would be really
appreciated!

Thanks,
BR/Pablo

PS: There may be an easy way out: creating a separate dcache xrootd
door, with a different port and a fake root
/pnfs/lcg.cscs.ch/cms/trivcat, and point the redirector to it... but it
seems to me much more dirty, compared with a generic xrootd (that could
equally serve ATLAS and CMS both) and a good name translation mechanism.

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