Status

SL6 at Zeuthen is the default and recommended Linux version:

• It has been the default operating system for all new systems for several years.
• The complete compute farm, most workgroup servers and the majority of desktops are running it.
• Users and groups are encouraged to request upgrading their remaining desktop and WGS systems

A test system is available: A virtual machine with an alias name of sl6.zeuthen.desy.de has been set up with a WGS configuration. It is meant to be used for tests and development, not for running production jobs.

SL6 presentations

• Technical Seminar, Zeuthen, 2012-01-10

• DESY Linux Users Meeting, Hamburg, 2012-04-13

Changes w.r.t. SL5 from the user's point of view

Enhancements

• SL6 makes use of more power saving features available in current hardware, resulting in significant savings especially on (partially) idle systems. This will not only reduce the institute's energy bill and help keeping the server rooms cool: Current desktop systems will also dissipate less heat and generate less noise.

• sshfs is available on desktops and WGSs. If a filesystem is available on a WGS, but not on your desktop computer, running mkdir /some/mount point; sshfs my-wgs:/some/filesystem /some/mount/point will make it available. To unmount, run fusermount -u /some/mount/point. For details, please consult the sshfs(1) manpage.

• On desktop systems, the local user can install additional software packages

• GPU computing support - CUDA is installed on systems supporting it

  • GPGPU farm nodes with Tesla cards
  • the latest desktop model (for getting started, development, test)

• VLC available as multimedia player

  • you have to install it on your own ( Gnome menu: System -> Administration -> Add/Remove Software )

  • as the development process of multimedia libraries is incompatible with "Enterprise Linux Distributions" like SL6, VLC's availability is not guaranteed over SL6's lifetime - in case of security issues VLC will be removed from all systems

• CVMFS access available on every desktop

  • configured repositories: *.cern.ch , *.desy.de , *.egi.eu , *.icecube.wisc.edu , *.opensciencegrid.org

General changes

• The default locale is now en_US.UTF-8

  • If you prefer the old default, or have trouble with UTF8, you can set LANG=C in ~/.i18n .

  • UTF8 doesn't make things faster or use less memory. It may be a good idea to run jobs under LANG=C.

• The AFS sysname list only goes back to SL4: amd64_rhel60 amd64_rhel50 i586_rhel50 amd64_linux26 i386_linux26.

• Under /afs, only the local cell shows up by default.

  • You can access other cells like /afs/cern.ch though. You just need to know they exist.

  • This prevents graphical file managers from digging through all foreign AFS cells.

• The default PATH now has the directories /usr/local/sbin:/usr/sbin:/sbin appended

  • on SL6, the shell will find some commands it won't on SL5 or SL4

• KDE is not installed by default, and has received close to no testing.

  • GNOME is recommended. IceWM is available.

  • Users who absolutely must have KDE can install it on Desktops themselves

    • In GNOME, select System -> Administration -> Add/Remove Software, and installed the "KDE Desktop" package collection

    • kdepim (korganizer) is not available though, since the akonadi backend wouldn't work

• The automounter is configured to mount only those file systems expected to be required on a system

  • Thus, on desktops, the automounter is not running at all because the NFSv3, pnfs and Lustre file systems it handles are not considered secure to export to desktops anyway.

• A soft limit of 1024 user processes applies by default. This is an upstream change intended to prevent accidental fork bombs, which makes sense but may prevent a few legitimate and reasonable use cases. Since it's a soft limit, users can raise it if required (ulimit -u 2048).

Changes regarding software

• /opt/products is almost empty. Software installed there in the past is now preferably provided using the normal SL packages, or in /opt.

• In many cases, there is no longer a default version if several releases of a software are installed. For example, instead of maple, run 'maple15 or maple16. Or use ini. But see the next item:

• The (DESY specific) ini command is being replaced by the more standard module one from the Environment Modules project. In many cases, both ini and module can still be used, but module is the future. See Getting started with environment modules.

• The spell checker is now hunspell and no longer aspell as on SL5 and ispell as on earlier SL releases. Unfortunately, an aspell command is available but is a useless stub, and an ispell command is available but is a compatibility wrapper script not working for all applications. Worst of all, a command spell is available too, and it's the useless aspell.

• The Grid gLite user interface (ini glite) is unsupported, please use the EMI-UI instead (source /project/grid/etc/profile.d/setup-grid-ui.sh). Further details can be found here.

Limitations

• Only 64-bit systems are available. We still install all relevant 32-bit compatibility packages.

• On desktops, only the nogroup setup is supported.

  • No permanent storage (/usr1/scratch). Please use central storage instead, possibly from a WGS. The /tmp file system is of course available. Files there are deleted two weeks after they were last accessed.

  • No remote login. Please use your WGS instead.

  • Console login for any user, independent of group.

• The local firewall is enabled, and all incoming ports closed by default.

  • This breaks qrsh on desktops. Please use it on a WGS instead.
  • Please let us know if you need additional ports opened for your work.

Software no longer provided

• ROOT

  • In 2011, DV/IT stopped providing new ROOT versions centrally and groups are expected to have their own installation tailored to their needs. This being said, there seem to be ROOT versions installed in /afs/desy.de/products/root .

• CERNLIB (obsolete since 2000, native SL6 build no longer works correctly)

  • Users who still must use parts of cernlib can find the SL5 build in AFS.

    • For example, to use paw:  env CERN=/afs/ifh.de/amd64_rhel50/products/cernlib /afs/ifh.de/amd64_rhel50/products/cernlib/2005/bin/paw

      • This was tested only superficially, and if it doesn't work there's not much we can do about it.

• The pine command has been an alias for alpine for half a decade, and is no longer available. Simply use alpine instead.

• Adobe Reader was removed for security

Known Problems

• emacs still uses spell instead of hunspell by default, although it's supposed to be fixed in the last update (which replaced our patched build) - great QA!

• For some users, nedit reportedly crashes when run remotely. We are unable to reproduce this. Workaround: running

  XLIB_SKIP_ARGB_VISUALS=1 nedit

  is reported to work for those users experiencing the problem.

• The tcl/tk versions have changed, and there are no compatibility libraries available. Software linked against libtcl/libtk will have to be rebuilt.

  • If there is significant demand for it, such a compatibility package could be provided by -DV-.