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Using CVMFS to serve site software

Using CVMFS to serve site software. Sarah Williams Indiana University. Motivation. Reduce dependence on NFS, because NFS is Not easily scalable Does not perform well on WAN Network policies often prohibit it across campus boundaries CVMFS solves these issues

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Using CVMFS to serve site software

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  1. Using CVMFS to serve site software Sarah Williams Indiana University

  2. Motivation • Reduce dependence on NFS, because NFS is • Not easily scalable • Does not perform well on WAN • Network policies often prohibit it across campus boundaries • CVMFS solves these issues • Scales with the number of squid servers. Load on apache backend is trivial • Local squid solves WAN issue • Network admininstrators are comfortable with HTTP traffic • Does not perform well on large (2Gb+) files, not a problem for our software installations

  3. Setup • Setting up a CVMFS-server requires: • A server with a copy of the files to be served, running CVMFS-server • Modification to worker nodes to mount the CVMFS repo and symlink to it • Use scheduling policy to prevent jobs on worker nodes that require write access to $APP– ie ATLAS install jobs, Engage

  4. CVMFS Server Configuration • CVMFS server used to provide access to $APP, /etc/grid-security/certificates, and wn-client • cvmfs-server runs on file server hosting $APP • Install procedure is in CVMFS technical report, p.16 • Every thirty minutes, the repo is updated: • Make copies of $APP, CA and wn-client to CVMFS shadow dir. Admins at Nebraska report that if you attempt to use $APP directly it causes file locking issues. • Set ownership to the CVMFS user • Run cvmfs-sync and cvmfs_server publish • http://repo.mwt2.org/viewvc/admin-scripts/cvmfs/cvmfs-update.sh?view=markup • Once a week, run cvmfs_server resign • If needed, modify setup.sh.local in $APP to check for local site config so that site-specific squid can be used • [ -f /share/local/setup.sh.local ] && source /share/local/setup.sh.local

  5. Worker node Configuration • Copy the public key created during install to the keys directory on the worker nodes, ex /etc/cvmfs/keys/osg.mwt2.org.pub • Create a config file for the repo, ex. • CVMFS_SERVER_URL=${CERNVM_SERVER_URL:="http://cvmfs.mwt2.org/opt/@org@"} • CVMFS_PUBLIC_KEY=/etc/cvmfs/keys/osg.mwt2.org.pub • The repo is mounted on /cvmfs/osg.mwt2.org/, and then create a symlink to the correct locations, ie: /etc/cvmfs/config.d/osg.mwt2.org.conf • /etc/grid-security/certificates -> /share/certificates -> /cvmfs/osg.mwt2.org/CA • /osg/mwt2/app ($APP) -> /share/osg/mwt2/app -> /cvmfs/osg.mwt2.org/app • /share/wn-client -> /cvmfs/osg.mwt2.org/wn-client

  6. Questions and Support • For cvmfs-server support, contact cvmfs-talk@cern.ch • Or email me and we can compare notes

  7. References • http://cernvm.cern.ch/portal/filesystem • http://www.hep.wisc.edu/cms/comp/ops/cvmfs.html • https://cernvm.cern.ch/project/trac/downloads/cernvm/cvmfstech-2.0-1.pdf

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