CERN Accelerating science


For more details, you can take a look at the BOINC site FAQ and message boards with live chat function.

We have assembled here some of the most common questions from the forums.

What do I need to participate in LHC@home?

You need a computer connected to the Internet with at least 512MB of RAM and 9GB of free hard disk space. It can run Windows, MacOSX or Linux.

To run any of our LHC@home applications, you will need to install BOINC.

For other applications than Sixtrack, you will also need to install VirtualBox.

For more information, please see our installation guide.

Last updated: 24 Nov 2016

Where can I find help?

See Contact Us where you'll find links to the forums, the Q&A for each project, and a contact form if you're really stuck.

We have a great community that will try to help you.

Last updated: 02 Jul 2015

Why are we using desktop computers instead of the Grid?

The computing needs of the LHC, especially when it comes to comparing various theories with experimental results, are enormous. Basically, the physicists' appetite for computing power expands to fill all available resources, because there are always more theories to test than there are computers to test them with.

Since budgets are constrained, especially in these economically difficult times, access to volunteer resources is seen by CERN as a great opportunity to expand computing capacity. We'll never replace the Grid's core function of managing the data mountains, but we could augment its computing power considerably. While the LHC World-Wide Computing grid is used at full capacity to handle the analysis of LHC data, there is need for additional capacity for simulations of LHC physics, ranging from theory to simulations of detectors as well as design improvements for future accelerators.

It's also clear to everyone in our community that getting the public more directly involved in LHC physics has great outreach benefits as well. So we see this as a win-win situation. And who knows, perhaps one day we'll be able to announce an important discovery that will have been made in part thanks to the volunteers. That would be cool!

Last updated: 09 Jun 2015

How am I helping scientists by contributing to LHC@home?

By contributing to LHC@home, you are helping physicists who seek fundamental answers about our Universe.  

Your computing contributions are used to improve the instruments used by particle physicists at CERN to perform better experiments in the future.

Last updated: 09 Sep 2019

Are any of my personal data sent to CERN when I install the software? What information about my machine is sent?

You will only have to provide a user name and an e-mail, nothing else is required. The information that is sent about your machine is the hardware specifications: CPU type, RAM and disk space, OS version, etc.

If you decide to leave the project, you can delete the data associated to your account from the LHC@home server.

Last updated: 09 Sep 2019

Why are VM applications not working on my machine?

See Yeti's check list in the forums.

Last updated: 06 Jun 2017

What is the specification for each application?

Here are the memory and disk requirements for running a single task of an application.


Requires 512MB of RAM and 1GB of free hard disk space.


Requires 630MB of RAM and 3GB of free hard disk space ( 0.8GB uncompressed disk image size ) plus ~1GB of RAM overhead for the host operating system.


Requires 1.4GB of RAM and 4GB of free hard disk space ( 2.2GB uncompressed disk image size ) plus ~1GB of RAM overhead for the host operating system.


Requires 2GB of RAM and 4GB of free hard disk space ( 1.7GB uncompressed disk image size ) plus ~1GB of RAM overhead for the host operating system.


Requires 2GB of RAM and 8GB of free hard disk space ( 3.9GB uncompressed disk image size ) plus ~1GB of RAM overhead for the host operating system.


Last updated: 23 Nov 2016

Can I run LHC@home projects offline? Or do I need my internet connection running?

See the forum thread here: In a nutshell:

You will need to have an open internet connection while running project tasks. You cannot run the tasks if not connected to the internet.

The task starts up a VM, then the VM runs a series of tasks that each run for about 60 to 90 minutes each. At the beginning of each task inside the VM, it downloads some data, crunches the numbers, and uploads the result, then the next VM task starts and downloads more data.

Last updated: 02 Jul 2015

Can I simply shut down my computer or is a special procedure necessary?

We recommend to exit BOINC before powering off the computer, because the VBox Wrapper will capture that exit signal, and will try to save the virtual machine and avoid canceling the WU. This is not necessary when suspending or hibernating the computer.

Last updated: 09 Jun 2015

Does LHC@home support GPUs?

For the moment LHC@home does not use GPUs for running the experiments. Additionally, the GPU code could not work as we are accessing the hardware via a virtual machine.

Last updated: 09 Jun 2015

I tried to install it, but it was too complex I gave up...

We know it, and for this reason we are working together with the BOINC and VirtualBox communities to simplify the whole process to set up the software and join us. It will be interesting if you can tell us where you have difficulties, please use the forums, so we can try to fix them for the next releases.

Last updated: 04 Jun 2015

Is it possible to configure the maximum amount of data that can be downloaded/uploaded by the project per month?

The BOINC transfer at most network preference is not supported for the moment. If your ISP has a limitation in the bandwidth that you can use each month, bear in mind that the virtual machine will continue downloading/uploading data when needed.

Last updated: 04 Jun 2015

My firewall is complaining. Which ports does this project use?

The ports required depends on the application however there are a few common ports:

  • HTTP (port 80)
  • HTTPS (port 443)
  • CVMFS (port 3125)


  • HTTP (Ports 8000, 8080, 23128)
  • HTTP Proxy (Port 3127, 3128)
  • XMPP (Port 5222)
  • TCP Port 9094

Theory and CMS and LHCb

  • Condor (9618)


  • WMAgent (4080)
  • Frontier (8080)
  • EOS (1094)


  • DIRAC (ports 8443, 9133, 9135, 9148, 9149, 9166, 9196, 9199 )
Last updated: 19 Dec 2019

BOINC client message: LHC@home: Notice from server: VirtualBox is not installed - What to do?

If you just want to run the Sixtrack application, you can safely ignore this message.  Otherwise, if you wish to run other applications like ATLAS, CMS or LHCb that require virtualization, you need to install Oracle Virtual Box as described in the "Install Virtual Box" entry. 

There is an issue with dependencies between VirtualBox and BOINC on some Linux distributions.

If you are running e.g. Ubuntu Linux, have already installed BOINC and VirtualBox, and still get a message from the BOINC client: VirtualLHC@home: Notice from server: VirtualBox is not installed 

To get the BOINC-VirtualBox combo to work properly on Ubuntu, please proceed as follows:

  • If not already done, install BOINC and VirtualBox from the Ubuntu repositories (with apt-get).  Then please execute:
  1. sudo service boinc-client stop 
  2. mkdir -p ${HOME}/boinc 
  3. boinc -dir ${HOME}/boinc 
  4.  boincmgr 

With this setup, the BOINC client puts all the temporary files in a directory called boinc under your home directory, and it is easy to see what is going on and avoid permission issues or similar.

Last updated: 28 Mar 2017

I'm using a Proxy for my Internet connections. Could this be a problem?

If you only have access to Internet via a Proxy, you may get Compute Errors in BOINC, as the Virtual Machine needs direct connection to Internet. For the moment there is no solution, but we will try to fix it.

Last updated: 16 Jun 2016

I'm getting the following message: Computation Error output file absent. What can I do?

First of all, HAVE YOU INSTALLED VirtualBox ??

Next, check that your BOINC installation sets up the correct permissions for running VirtualBox. Recheck our information on "Installing BOINC".

If BOINC is correctly installed, the main reason for that message is that the wrapper fails to remove an old virtual machine (VM) after it has expired, and so cannot register a new VM for the next Work Unit (WU).

The best solution for cleaning your project files if you have to do it manually is:

  1. Abort the running WU.
  2. Quit BOINC (the core client should be not running).
  3. Open VirtualBox Manager, and remove the registered machine named "BOINC_VM" (or any VM's with names "boinc_wu_xxxx_xxx").
  4. Open VirtualBox Media Manager and remove the cernvm.vmdk virtual hard disk if it is registered.
  5. Launch BOINC again.
Last updated: 02 Jul 2015

How do I report an error or a bug?

If you have found an error or a bug in the application, the experiments, the project, etc. please write a post about the error in the message boards so the administrators and volunteers can participate in solving the problem.

Last updated: 12 Jun 2015

The Virtual Machine uses my CPU too intensively. How can I change this?

You can change how much CPU time is used by the Virtual Machine going into your BOINC project account and changing the Preferences for this project -> Maximum CPU % for Virtual Machine. You can specify an amount between 0 and 100% (by default 100%), then save your preferences and update the BOINC project.

Last updated: 09 Jun 2015

Why is my old web browser not supported?

The web application provided in the virtual machine uses JavaScript, HTML5 and CSS3 to show the results and your BOINC credit, using technologies like JavaScript, JSON and HTML5.

If you cannot enable JavaScript in your browser's settings or your browser does not support HTML5 and/or CSS3, you will be missing a friendly user interface to the results:

  • an interactive gallery with all the figures from the simulations of your computer:
    • zoom in and out with a friendly interface,
    • browse the figures (next,previous and index) using shortcuts and without going back and forward to see other image,
    • swipe movement for flicking through images on touch devices,
    • etc.
  • and some BOINC statistics.

Here you have an screenshot of the web page with a free, modern and open source web browser like Mozilla Firefox or Google Chrome (but note that Safari versions 6+ and Internet Explorer versions 10+ do support our graphics):

You can still access the raw figures and BOINC stats data and the LOGs folder as you will get a warning with links to those resources.

Last updated: 09 Jun 2015

VirtualBox shows me the following runtime error message: "cannot access the kernel driver!" What can I do?

(This is a Windows problem only).If you get that error it seems like your VirtualBox installation missed installing the vboxdrv.inf driver. Please first try to reinstall VirtualBox - if this does not solve the problem, go to C:\Program Files\Oracle\VirtualBox\Drivers\ and double click in the file vboxdrv.inf. After that, you should be able to run VirtualBox without problems.

Last updated: 04 Jun 2015

My keyboard and mouse do not respond to me. How can I get them back?

If you click inside the console window of the Virtual Machine and the keyboard and mouse get "grabbed" in the window, then to release them, you have to press the Host Key (Right Ctrl) or (Right Cmd in Mac OS X). You can check which is the Host Key by clicking in: File->Preferences->Input

Last updated: 04 Jun 2015

Message boxes keep popping up from Virtualbox. How can I remove them?

VirtualBox warns the user about how the keyboard and mouse will be captured if you click inside the window of the virtual machine. This message will pop up everytime you run a virtual machine unless you tick the "don't show this window again" option in the message box.

Last updated: 04 Jun 2015

VirtualBox crashes and does not respond at all to BOINC. What can I do?

If the virtual machine named "boinc_wu_xxxx_..." in the VBox Manager window does not respond at all to BOINC (i.e. you suspend the BOINC task but the VM is still running) you can try the following steps to recover the project:

  1. Abort the running WU and exit BOINC. Then, you will have to manually kill or quit the VirtualBox process from a command line. It will be different in each operating system, but usually:
    1. In Mac OS X: you can kill it using the Terminal interface and running the kill -9 command to kill the PID of the process "VBoxHeadless.exe".
    2. In GNU/Linux: you can kill the VirtualBox process using your Desktop manager or from a terminal using the kill -9 command to kill the PID of the process called "VBox Headless".
    3. In Windows: open the Windows task manager and kill the VirtualBox process.
    4. Restart BOINC: it should receive a new clean WU and everything should be working OK again. If at this point you are still having problems, please use the message boards to get more help.
Last updated: 04 Jun 2015

I installed BOINC in Windows with the "Protected Application Execution" option. Could this be a problem?

If you have installed BOINC with the Protected Application Execution option enabled, then you will not be able to run the project, and all the work units will fail. The reason is that when you install BOINC with that flag enabled, BOINC is run under an unprivileged user that cannot create, start, pause, resume virtual machines at all. Thus, the wrapper will not be able to run the required virtual machine of this project.

In order to solve it, please, reinstall BOINC with that option disabled.

Last updated: 19 May 2015

I'm getting lots of errors and I have BOINC installed as a service/daemon, is this a problem?

BOINC must not be installed as a service (Windows) or a daemon (GNU/Linux) because this project uses Virtual Machines. When BOINC is installed as a service or a daemon it runs as an unprivileged user and cannot run any virtual machine.

The best solution to solve this problem under Windows is to install BOINC disabling the Service option in the Windows installer.

Late news: BOINC Client 7.2.10 and above solve this problem for running as a service under Windows.

For GNU/Linux users the recommendation is to use the official BOINC GNU/Linux installer instead of the packaged ones for your distribution.

Last updated: 19 May 2015

What is Virtualization?

Virtualization, in computing, is the creation of a virtual computer that can run an operating system, applications, etc. within your real hardware. You can obtain more information about this topic in the Wikipedia.

Last updated: 09 Jun 2015

What is VirtualBox?

VirtualBox is a powerful x86 and AMD64/Intel64 virtualization hypervisor for enterprise as well as home use. A hypervisor allows your computer to host one or more Virtual Machines, running different operating systems than your own computer runs. This is essential for all our projects (except for Sixtrack).

Not only is VirtualBox an extremely feature rich, high performance product, it is also the only professional solution that is freely available as Open Source Software under the terms of the GNU General Public License (GPL) version 2.
Last updated: 09 Jun 2015

Why do we need a virtualization application?

All our projects (except for Sixtrack) run very large CERN software packages with complex dependencies that cannot be easily ported to all the volunteers' operating systems (Windows, GNU/Linux and Mac OS X).

For this reason, we use a virtualization solution, which enables us to run complex codes independently of your platform.

Additionally, using virtualization adds an extra layer of security, as if something goes wrong in the code execution this will not affect your computer.

Last updated: 09 Jun 2015

Why is the Virtual Machine not using all my CPU cores?

VBoxWrapper does not support more than 1 core currently. We recommend you run multiple BOINC tasks, each with a single VM, to use multiple cores on your system.

Last updated: 09 Jun 2015

What simulation packages are included in CernVM?

 Many packages are included in CernVM. For example, Test4Theory is based on the RIVET analysis tool and includes the following high-energy physics event generators:  ALPGEN,  HERWIG++,  PYTHIA,  SHERPA, and  VINCIA

Last updated: 09 Jun 2015

What is CernVM?

CernVM is a Virtual Software Appliance for the participants of CERN LHC experiments. The Appliance represents an extensible, portable and easy to configure user environment for developing and running LHC physics software both locally, on Grids and on Clouds, independently of Operating System software and hardware platforms (GNU/Linux, Windows, MacOSX).

The goal is to remove a need for the installation of the experiment software on each target platform, and thus to minimize the number of platforms (compiler-OS combinations) on which experiment software needs to be supported and tested. Visit the CernVM homepage for further details.

Last updated: 04 Jun 2015