Getting Started

This section describes how to install the CernVM-FS client. The CernVM-FS client is supported on x86, x86_64, and ARM architectures running Linux and macOS \(\geq 10.14\) as well as on Windows Services for Linux (WSL2). There is experimental support for Power and RISC-V architectures.


The CernVM-FS repositories are located under /cvmfs. Each repository is identified by a fully qualified repository name. On Linux, mounting and unmounting of the CernVM-FS is usually controlled by autofs and automount. That means that starting from the base directory /cvmfs different repositories are mounted automatically just by accessing them. A repository will be automatically unmounted after some automount-defined idle time. On macOS, mounting and unmounting of the CernVM-FS is done by the user with sudo mount -t cvmfs /cvmfs/... commands.

Getting the Software

The CernVM-FS source code and binary packages are available from the CernVM website. However, it is recommended to use the available package repositories that are also provided for the supported operating systems.


To add the CVMFS repository (available for Debian and RHEL flavors) and install CVMFS, run:

sudo yum install
sudo yum install -y cvmfs
sudo dpkg -i cvmfs-release-latest_all.deb
rm -f cvmfs-release-latest_all.deb
sudo apt-get update
sudo apt-get install cvmfs
sudo dnf install \

Other Platforms

The CernVM-FS service container can expose the /cvmfs directory tree to the host. Import the container with

docker pull

or with

curl | docker load

Run the container as a system service with

docker run -d --rm \
  -e,... \
  --cap-add SYS_ADMIN \
  --device /dev/fuse \
  --volume /cvmfs:/cvmfs:shared \

Use docker stop to unmount the /cvmfs tree.


If you run multiple nodes (a cluster), use -e CVMFS_HTTP_PROXY to set a proper site proxy as described further down.

On Mac OS X, CernVM-FS is based on macFUSE. Note that as of macOS 11 Big Sur, kernel extensions need to be enabled to install macFUSE. Verify that fuse is available with

kextstat | grep -i fuse

Download the CernVM-FS client package in the terminal in order to avoid signature warnings

curl -o ~/Downloads/cvmfs-2.11.3.pkg

Install the CernVM-FS package by opening the .pkg file and reboot. Future releases will provide a signed and notarized package.

A native package for Apple Silicon M1/M2 … processors is available as well, use the following command instead:

curl -o ~/Downloads/cvmfs-2.11.2-applesilicon.pkg

Future releases will provide a package with universal binaries.

Follow the Windows instructions to install the Windows Subsystem for Linux (WSL2). Install any of the Linux distributions and follow the instructions for the distribution in this guide. Whenever you open the Linux distribution, run

sudo cvmfs_config wsl2_start

to start the CernVM-FS service.

Setting up the Software

Configure AutoFS

For the basic setup, run cvmfs_config setup. This ensures that the file /etc/auto.master.d/cvmfs.autofs exists containing /cvmfs /etc/auto.cvmfs and that the autofs service is running. Reload the autofs service in order to apply an updated configuration.

NB: For OpenSUSE uncomment the line #+dir:/etc/auto.master.d/ in the file /etc/auto.master and restart the autofs service.

sed -i 's%#+dir:/etc/auto.master.d%+dir:/etc/auto.master.d%' /etc/auto.master
systemctl restart autofs

Mac OS X

Due to the lack of autofs on macOS, mount the individual repositories manually like

sudo mkdir -p /cvmfs/
sudo mount -t cvmfs /cvmfs/

For optimal configuration settings, mount the config repository before any other repositories.

Create default.local

Create /etc/cvmfs/default.local and open the file for editing. Select the desired repositories by setting CVMFS_REPOSITORIES=repo1,repo2,.... For ATLAS, for instance, set,,

For an individual workstation or laptop, set


If you set up a cluster of cvmfs nodes, specify the HTTP proxy servers on your site with


If you’re unsure about the proxy names, set CVMFS_HTTP_PROXY=DIRECT. This should only be done for very few clients (< 5), because large numbers can put a heavy load on the Stratum 1 servers and result, amongst others, in poorer performance for the clients. For the syntax of more complex HTTP proxy settings, see Network Settings. If there are no HTTP proxies yet at your site, see Setting up a Local Squid Proxy for instructions on how to set them up.

Verify the file system

Check if CernVM-FS mounts the specified repositories by cvmfs_config probe. If the probe fails, try to restart autofs with sudo systemctl restart autofs.

Building from source

The CernVM-FS client is not relocatable and needs to be installed under /usr. On Intel architectures, it needs a gcc \(\geq 4.2\) compiler, on ARMv7 a gcc \(\geq 4.7\) compiler. In order to compile and install from sources, use the following commands

cd <source directory>
mkdir build && cd build
cmake ../
sudo make install

Building with local libraries

For development purposes it might be useful to use locally installed libraries instead of using default system libraries. This can be done by defining variables during the cmake configuration step. The correct naming of the variables can be found in cmake/Modules. For example, in case of Fuse3 following variables must be set: FUSE3_INCLUDE_DIR and FUSE3_LIBRARY.

Furthermore, CMAKE_INSTALL_RPATH_USE_LINK_PATH:BOOL=ON must be set, otherwise will sudo make install strip all linked libraries that point to none-system libraries.

Example code for building CernVM-FS with locally built Fuse3 and including the CernVM-FS unit tests and gateway:

      -D FUSE3_INCLUDE_DIR=/usr/local/include/ \
      -D FUSE3_LIBRARY=/usr/local/lib/x86_64-linux-gnu/ \
sudo make install


  • In order to check for common misconfigurations in the base setup, run

cvmfs_config chksetup
  • CernVM-FS gathers its configuration parameter from various configuration files that can overwrite each other’s settings (default configuration, domain specific configuration, local setup, …). To show the effective configuration for, run

cvmfs_config showconfig
  • In order to exclude autofs/automounter as a source of problems, you can try to mount manually with the following

mkdir -p /mnt/cvmfs
mount -t cvmfs /mnt/cvmfs
  • In order to exclude SELinux as a source of problems, you can try mounting after SELinux has been disabled by

/usr/sbin/setenforce 0
  • Once the issue has been identified, ensure that the changes are taken by restarting autofs

systemctl restart autofs
  • If the problem is that a repository can be mounted and unmounted but later cannot be remounted, see Remounting and Namespaces/Containers.

  • In order to exclude a corrupted local cache as a source of problems, run

cvmfs_config wipecache
  • Finally running with debug logs enabled can provide additional information for bug reports. This can be done by specifying a log file path in the client settings, e.g: CVMFS_DEBUGLOG=/tmp/cvmfs.log. See Debug Logs for more details.