Prerequisites

The primary requirement for analyzing the Run 1 LHCb Open Data DSTs hosted on the CERN Open Data Portal is a working setup of the CERN Virtual Machine File System (CVMFS). Through the CVMFS, the LHCb software environment is distributed, providing all of the necessary components for analysis of LHCb data.

Setting CVMFS

The CVMFS is a software distribution service. In other words, it is a service that allows the user to have all the CERN software infrastructure at hand. CMVFS can be installed on a variety of platforms. The following code block shows the installation process in Ubuntu:

# The following lines encompass the installation of CVMFS
wget https://cvmrepo.s3.cern.ch/cvmrepo/apt/cvmfs-release-latest_all.deb
sudo dpkg -i cvmfs-release-latest_all.deb
rm -f cvmfs-release-latest_all.deb
sudo apt-get -y update
sudo apt-get -y install cvmfs

The following instructions are OS-independent!

Once CVMFS is installed we need to run the following commands:

# Configure autoFS
cvmfs_config setup

# Create the file "default.local"
touch /etc/cvmfs/default.local

In this tutorial, we will work with the LHCb environment. Inside default.local we have to include two parameters to work with the LHCb environment:

CVMFS_REPOSITORIES=lhcb.cern.ch,lhcb-condb.cern.ch,lhcbdev.cern.ch
CVMFS_CLIENT_PROFILE=single

Testing CVMFS

The first test is to check if CVMFS mounted the necessary repositories:

cvmfs_config probe

If the probing process is OK, we can now source LbEnv and start using the LHCb software machinery:

source /cvmfs/lhcb.cern.ch/lib/LbEnv