Scientific Linux CERN 4 (SLC4) is not supported anymore (general user support ended in Dec 2010, experiment support in June 2013)

Linux @ CERN

CERN > IT > OIS > Linux

What is Scientific Linux CERN 4 (SLC4)

Scientific Linux CERN 4 is a Linux distribution build within the framework of Scientific Linux which in turn is rebuilt from the freely available Red Hat Enterprise Linux 4 product sources under terms and conditions of the Red Hat EULA. Scientific Linux CERN is built to integrate into the CERN computing environment but it is not a site-specific product: all CERN site customizations are optional and can be deactivated for external users.

Originally SLC4 was foreseen to be just a safety net in case SLC5 could not be certified in time, without major deployments foreseen (see our CNL article on this). However, our previous estimate of a RHEL5 release for mid-2006 does no longer look realistic. Fermi and CERN Linux experts now expect RHEL5 and hence SL5 to be available only at the beginning of 2007 (see the current SL roadmap). Hence, the CERN-certified variant of SL5, SLC5, could at earliest be available at the end of 1Q2007.

Since the original deadline of having a stable SLC5 distribution in October 2005 can not be met, SLC4 will be used in several key areas at LHC startup.

Scientific Linux CERN 4 Support Lifetime

Since SLC/SL are based on sources of Red Hat Enterprise Linux 4 (RHEL4) sources its support lifetime cannot be longer than the one proposed by Red Hat. Due to CERN environment constraints (available manpower, hadrware purchases procedures .. etc.) Scientific Linux CERN 4 Lifetime may be actually shorter than RHEL4 one, subject to Linux Certification Committee decision.
At present following End of Support dates are foreseen:

As presented on June 2010 and October 2010 IT Technical Users meetings, (see:, CERN login required, see: IT Technical Users Meeting June 2010 presentation (local copy) and IT Technical Users Meeting October 2010 presentation (local copy)) the General user support for SLC4 ENDED on 31st of December 2010. Since that date user requests for SLC4 support and/or installation are rejected by service desk.

Dedicated support for experiments and accelerator controls will be maintained for three months after 2011 LHC shutdown beginning but no longer than February 2012 2013.

In addition to the above dates please note that since August 2007 we do not accept any request for new features. Since February 2008 only security updates are provided (except for CERN-specific software included). From March 2012 RHEL4 support will be not available anymore. (RHEL4 product support life cycle)


Certification status

  • Formal certification has started 04.10.2005 and ended on 31.03.2006 on which date Scientific Linux CERN 4 (SLC4, SLC 40X) has been certified to use at CERN
  • The separate status page has the current status.

    Certification goals / announced changes

    Prelimiary goals, to be discussed with the CERN user community

    Also being collected on the Linux Support internal Wiki.

    Current SLC4 release

    Current release is Scientific Linux CERN 4.8 released on 12.08.2009. It merges all updates released since previous releases in the installation tree.