LINUX upgrade required to keep operating systems up to date

Currently most of the nodes providing the LXPLUS and LXBATCH services at CERN run a tailored version of the Red Hat 7.3 LINUX distribution.

Red Hat released a new version called Red Hat Enterprise server 3 (RHES3) some time ago and no longer supports 7.3. CERN and other HEP sites, notably Fermilab, have decided to standardize on their own compilations of the RHES3 open source that contains packages needed for scientific computing and is fully binary-compatible with RHES3. This packaging is termed Scientific LINUX 3.

There are local differences between CERN and Fermilab, such as the version of AFS/Kerberos; the version at CERN is called SLC3 (Scientific LINUX CERN RHES3) and is currently under certification testing by the LHC experiments. An important change for them is that the default and only gcc compiler and libraries change to version 3.2.3. In Red Hat 7.3 versions 2.96 (the default), 3.2.2 and 3.2.3 were all available.

We need to migrate all our services to this version as soon as possible since we cannot base production services on an unsupported operating system for long.

Currently the generic service name lxplus maps to about 70 PCs running Red Hat 7.3. In parallel, we have a cluster of PCs running SLC3 under the service name of lxslc3 and users, especially experiment-code and production-chain managers, should log in there, instead of to lxplus, to test their programs.

Batch submission from lxslc3 will automatically be to worker nodes also running the SLC3 operating system. All users are encouraged to try the service lxslc3 instead of lxplus. Eventually lxplus will be changed to point to lxslc3 - so be prepared!

There is a high degree of compatibility between Red Hat 7.3 and SLC3 and the main changes are described at the website http://cern.ch/linux/scientific3. An overview and specific issues for lxplus users are at http://cern.ch/plus/SLC3.html.

We have recently taken delivery of 400 new PCs which have faster CPU speeds of 2.8 GHz and 2 Gb of memory. Most of these nodes will be put into the lxslc3 interactive and batch services so users will see an improvement over the current lxplus which runs on 1.0 GHz CPUs which have 1 Gb of memory.

The SLC3 services will soon contain most of the new PCs and we will start converting existing machines to SLC3.

The service name to reach Red Hat 7.3 is already available under the name lxplus7. This will be continued on a small number of nodes after the changeover of lxplus but only as long as it is absolutely necessary.


Author

Harry Renshall, IT/FIO