End of the road for SLC3

Scientific Linux CERN 3 (SLC3), the old CERN Linux distribution, will be laid to rest this autumn. SLC3 was certified as the default CERN Linux version back in November 2004. Since SLC4 has been the CERN Linux production version for more than a year (and the default on LXPLUS and LXBATCH for more than six months), general support for SLC3 will end on 31 October. This date was agreed with all the major CERN Linux user communities in February 2006 because it was in line with the end of life of the "upstream" Scientific Linux 3.

This means that from 1 November:
• the Helpdesk will provide no more support for SLC3;
• no more SLC3 installations will be possible via the central install servers;
• and, most importantly, no SLC3 updates (security or otherwise) will be distributed from our servers.

The CERN computing rules (OC5 § II.12) require that all computers are protected proactively against attacks. Since CERN Linux support will no longer provide security updates for SLC3, it will be up to the machine owners (registered responsibles) to migrate their machines to our supported SLC4 (this is now the preferred Linux distribution, and users will receive automatic updates). Otherwise machine owners will be required to secure their machines, which will involve investing a lot of effort to make sure their machine does not create a security risk for the site.

The registered responsibles for SLC3 machines at CERN were sent several emails in July and will receive several more warnings. We may also have to communicate more directly with the users of affected machines, since experience shows that our warning mails sometimes go unheeded (for example, during the 7.3 phase-out). These warnings are intended to make sure that no SLC3 machines are unintentionally left insecure.

More information about this phase-out campaign and answers to frequently asked questions can be found at http://cern.ch/linux/slc4/docs/migration-campaign.shtml.

SLC4++, or what's next?

SLC4 is the current production version and will be so at the start-up of the LHC. It seems clear that none of the major user groups plans to switch the majority of their machines to a completely new Linux distribution until well after the start-up.

At the same time we are seeing more and more recent hardware that isn't supported by the now two-year-old SLC4; this affects laptops in particular, which are rather short-lived in terms of production lifetime.

Not all desktop models work well with SLC4 either (machines in the computer centre tend to demonstrate fewer problems, since fewer "features" are required to work on these). Even updating our distribution to the "upstream" Scientific Linux 5 will not solve all these issues.

This means that for now we see no urgent need to provide a supported SLC5 distribution, and, depending on our users' timelines, we might decide to skip SLC5 altogether in favour of a future SLC6.

At the time of writing, no decision has been taken and alternative solutions (such as just updating the Linux kernel) are still being discussed.