Comment 11 for bug 457702

The above fix calls reboot with the -f option to force a hard reboot without properly shutting down the system.

This is not always a good idea. The problem still exists when some other application (or the user) happens to issue a normal shutdown command.

Moreover, doing a hard reboot is not always a good idea. I have a couple of fat clients that I'd really rather shut down properly (so that e.g. the NFS mounted home directories are correctly flushed and umounted).

The real problem that has to be correct here is that sometime during the shutdown the network interface is deactivated. The NBD then becomes unavailable and the entire system freezes, since it cannot access the root file system anymore.

There is actually a check in /etc/init.d/networking that should prevent the network from being disabled when something is mounted from /dev/ndb, but either it does not work in this case or there is another script that shuts down the network.