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CernVM File System on Personal Workstations

About CernVM File System

The CernVM File System ("CernVM-FS" or "CVMFS") is a tool that allows for efficient global distribution of software and data that does not change frequently. Its name indicates its origins for use by virtual machines in use by the high energy physics community, however, it has wider applicability and usage. It caches files to disk so that, after the initial download, file access for the client is speedy.

Within LIGO, CVMFS is being used to distribute both instrument data ("frame files") and analysis software for use at LIGO computing sites and on the Open Science Grid (OSG). You may elect to install CVMFS on your workstation for ease of access to recent data and software. The MacOS CVMFS client cannot yet access LIGO instrument data, though it is hoped that that feature will be developed. You should pay attention to the LIGO Software Container as it is developed to see if it may facilitate access to instrument data on your workstation.


Scientific Linux 7

This condenses the installation into the essential steps. If you run into issues, please rely on the official OSG Documentation.

Begin by installing the LIGO, Open Science Grid (OSG), and Extra Packages for Enterprise Linux (EPEL) repositories, if you have not already. The priorities plugin will ensure that packages present in both will be drawn from the correct repository.
sudo yum install yum-plugin-priorities
sudo rpm -Uvh
sudo rpm -Uvh
sudo rpm -Uvh

Continue by installing CVMFS and the LIGO Data Grid Client for access to instrument data.
sudo yum install osg-oasis ldg-client

Finish by adding the following line to /etc/auto.master
/cvmfs /etc/auto.cvmfs

and restarting autofs
sudo systemctl enable autofs
sudo systemctl restart autofs


If you have not already installed the LSCSoft repository, follow these instructions. Then, install the required packages:
sudo apt-get update
sudo apt-get install cvmfs cvmfs-config-osg

If you are a LIGO-Virgo member and also want to access LIGO instrument data, you must also run
sudo apt-get install ldg-client cvmfs-x509-helper


  1. Install Fuse for MacOS (also available via MacPorts and Homebrew)
  2. Install CVMFS version 2.3.5 (current as of April 2017)
  3. You may skip the Configuration section and head directly to Usage.


CVMFS uses a technology called FUSE to access remote data. On MacOS, it will be configured correctly automatically. On both Debian and Scientific Linux, you must make one configuration change to FUSE for CVMFS to work properly. Cut-and-paste these commands exactly!
sudo sed -i 's/#[[:space:]]*user_allow_other/user_allow_other/' /etc/fuse.conf
cat /etc/fuse.conf

The 2nd command should show that the option user_allow_other is present and not commented. If it is not, use your favorite editor to add it to the file.

The configuration that is installed by default is only appropriate for the low amount of traffic one might expect from a single client. After testing usage, please consider setting some Advanced Configuration Options for improved performance.


At this point, anyone can find LIGO software such as pyCBC and lalsuite under
ls -lh /cvmfs/

If you are a LIGO-Virgo member and you are running CVMFS on Linux, you should be able to able access recent LIGO instrument data with the following commands.
ligo-proxy-init albert.einstein
ls -lh /cvmfs/

Advanced Configuration Options

The full range of CVMFS options are discussed in its documentation. These options should be set in /etc/cvmfs/default.local. Two important options are set in this file upon installation. If you make any changes, you must subsequently run
sudo cvmfs_config reload

Local cache for fast access


This tells your client to cache up to 20,000 MB of data on your workstation so that they are accessed at high speed. You can change it to any number you see fit.

Nearby cache for faster downloads

The default behavior of the client is to connect directly to "central" CVMFS servers that serve data from non-LIGO sites to LIGO computing sites. If you are at a LIGO computing site, it may be faster and cause less data usage for your internet connection to use a cache installed by your computing staff. If you configure a campus-based cache and take your laptop off-campus -- or are not actually at that campus! -- it will failover to a direct connection, although there may be a noticeable delay as it fails to connect to the campus-based cache. Recommended values for the CVMFS_HTTP_PROXY option are below.





Topic revision: r13 - 25 Sep 2017,

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