Restoring the root file system

If the physical file system owning the root fails, all work in progress when a failure occurs is lost, and it must be restarted from the beginning.

CAUTION:

Unmounting and remounting a root file system is disruptive to the system. Any work in progress must be undubbed and redubbed.

Rule: The person who restores a failed root file system or an unmounted root file system must be a superuser who is defined with a home directory of / (root).