7.8 Starting over - installing OSCAR again

If you feel that you want to start the cluster installation process over from scratch in order to recover from irresolvable errors, you can do so with the start_over script located in the scripts subdirectory.

It is important to note that start_over is not an uninstaller. That is, start_over does not guarantee to return the head node to the state that it was in before OSCAR was installed. It does a ``best attempt'' to do so, but the only guarantee that it provides is that the head node will be suitable for OSCAR re-installation. For example, the RedHat 7.x series ships with a LAM/MPI RPM. The OSCAR install process removes this RedHat-default RPM and installs a custom OSCAR-ized LAM/MPI RPM. The start_over script only removes the OSCAR-ized LAM/MPI RPM - it does not re-install the RedHat-default LAM/MPI RPM.

Another important fact to note is that because of the environment manipulation that was performed via switcher from the previous OSCAR install, it is necessary to re-install OSCAR from a shell that was not tainted by the previous OSCAR installation. Specifically, the start_over script can remove most files and packages that were installed by OSCAR, but it cannot chase down and patch up any currently-running user environments that were tainted by the OSCAR environment manipulation packages.

Ensuring to have an untainted environment can be done in one of two ways:

  1. After running start_over, completely logout and log back in again before re-installing. Simply launching a new shell may not be sufficient (e.g., if the parent environment was tainted by the previous OSCAR install). This will completely erase the previous OSCAR installation's effect on the environment in all user shells, and establish a set of new, untainted user environments.

  2. Use a shell that was established before the previous OSCAR installation was established. Although perhaps not entirely intuitive, this may include the shell was that initially used to install the previous OSCAR installation.

Note that the logout/login method is strongly encouraged, as it may be difficult to otherwise absolutely guarantee that a given shell/window has an untainted environment.

root 2002-11-08