Here are a few facts users of Ubuntu desktops should be aware of:

Access

• All user accounts valid at DESY Zeuthen can log in on the local graphical login screen.
• No remote access via ssh.

Local Home Directory

• Home directories reside on the local disk.

  • Please note that local disks are not redundant and may break or vanish otherwise anytime.

• There is no central backup.

  • It is recommended to arrange for a personal backup of the home directory with dejadup. It's "safe" icon is displayed in the dash by default. If not, just search for "backups".
• There is a 4 GB home quota.
  • We need to set a quota to keep things manageable. It avoids problems when desktops are used by more than one user, which is still a frequent case, and also keeps making backups feasible and consume reasonable amounts of resources.

If downloads etc. don't fit into the home directory, there's more local space available in /tmp. Files there will be cleaned up two weeks after they were last accessed. Unlike "usual" Ubuntu installations, /tmp/ is not cleared when our systems are rebooted.

AFS Client

• The AFS client may vanish with no or only a short warning

  • Ubuntu is much less conservative than EL about backporting ABI changes even to LTS kernels, including changes that could break the AFS client. Thus there's no guarantee for the continuous availability of an AFS client on Ubuntu desktops, which is also one reason for keeping the home directories local.

• There's no special sysname (list), and it's not foreseen to introduce one. Using @sys in AFS paths is deprecated.

Adding and Removing Software Packages

• Local users can use the "Packages" application to do this (the real name is gpk-application). Only the configured repositories are permitted package sources though.
  • These changes are not saved or recorded centrally, and will vanish when a system is reinstalled.

  • There is considerable potential for getting the system into a bad state, thus this feature should be used with care and thought.

• If you're into the command line rather than GUIs, you can use pkcon(1) instead. Just translate sudo apt-get install <package> into pkcon install <package>.

Reinstallation

• Anyone with access to the local console can reinstall the desktop from scratch. Requesting a network (PXE) boot during startup will result in presentation of a menu with all available desktop OS options to choose from.

• Note that a reinstallation will wipe the local disk and any prior content will be lost irrecoverably.

Miscellania

• While GNOME3 (gnome-shell) is the default and recommended desktop environment, it is possible though to install a plethora of others from the configured repos.

• Users can use the chsh command to change their login shell. The change is only effective on the local system though.

Known Issues

• choosing the keyboard layout on the gdm login screen doesn't work
• there's a report that gdm won't remember non-default session choices