NGI CZ:CVMFS for auger

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CVMFS for the VO auger


Historical introduction (can be skipped by impatient readers)

CVMFS is a distribution tool for software (and other relatively small files). It started to be used by LHC experiments, several other projects deployed it later, all with very good experience. LHC projects use master repository called stratum-0 based at CERN. The master repository for some other projects is hosted by RAL and is decribed at GRIDPP wiki page. VO auger is not supported by RAL site and we started a CVMFS repository hosted by OSG. RAL site can replicate the master repository and distribute it via the same stratum-1's as for other nonLHC VOs. However the path would change from /cvmfs/opensciencegrid/ to /cvmfs/auger.gridpp.ac.uk and the non-relocatable auger offline software would not work.


Setup for the VO auger

A new solution was discussed during EGI Communnity Forum 2014 at Helsinki and shortly after it adopted. A new stratum-0 with a base name egi.eu is hosted by RAL. VO auger software manager (currently not defined by the VOMS role, but by explicitly given list of DNs) can upload software to a repository server. Than a manual step by RAL CVMFS master Catalin Condurache is taken to copy the content to the stratum-0. Clients see the software in the path /cvmfs/auger.egi.eu/.


Clients setup

Software compilation

I compile the software directly an a worker node. This would immediately show missing packages. I assume that all WNs (at leaste on our sites) are installed identically and if it compiles and runs on one node, it should run on every node. However the  partition  /cvmfs/auger.egi.eu/ is mounted as read only. The solution is to do (on an offline WN):

mount -o bind /tmpfs/auger ''/cvmfs/auger.egi.eu/''

We tried also --make-private option, but it is supported only by newset kernels.


Links

| CVMFS documentation at CERN
| OSG CVMFS documentation



We thank to the EGI CVMFS task force and RAL for their support. Catalin Condurache was the key person for CVMFS support for nonLHC VOs.

--Chudoba 16:51, 11 July 2014 (CEST)