\section{Boot Process Failures}

\begin{frame}
   {Boot Process Failures}

   \begin{itemize}
      \item Follow the boot process
      \begin{itemize}
         \item \textbf{BIOS}
         \item \textbf{GRUB}
         \item Kernel
         \item \textbf{init}
      \end{itemize}
   \end{itemize}

\end{frame}

\cprotect\note{

   If the system fails to boot properly or fully, being
   familiar with what happens at each stage is important.
   Assuming you get through the \textbf{BIOS} stage, you
   may reach a state of:

   \textbf{No bootloader screen:}

   Check for \textbf{GRUB} misconfiguration or a corrupt
   boot sector.  Bootloader re-install needed?

   \textbf{Kernel fails to load:}

   If the kernel \textbf{panics} during the boot process, it
   is most likely a misconfigured or corrupt kernel, or
   incorrect kernel boot parameters in the \textbf{GRUB}
   configuration file.  If the kernel has booted
   successfully in the past, either it has corrupted, or bad
   parameters were supplied.  Depending on which, you can
   re-install the kernel, or enter into the interactive
   \textbf{GRUB} menu at boot and use very minimal command
   line parameters and try to fix that way.  Or you can try
   booting into a rescue image.

   \textbf{Kernel loads but fails to mount the root filesystem:}

   The main causes here are
   \begin{enumerate}
      \item Misconfigured \textbf{GRUB} configuration file.
      \item Misconfigured \filelink{/etc/fstab}.
      \item No support for the root filesystem type built
      into the kernel or in the  \textbf{initramfs} image.
   \end{enumerate}

   \textbf{Failure during the \textbf{init} process.}

   There are many things that can go wrong once \textbf{init}
   starts; look closely at the messages
   that are displayed before things stop.
   If things were working before, with a different kernel,
   that is a big clue.  Look out for corrupted
   filesystems, errors in startup scripts etc.  Try booting
   into a lower runlevel such as \texttt{3} (no graphics) or
   \texttt{1} (single user mode).

}



