The time comes when every Linux system administrator experiences a system failure. Hardware failures are usually resolved quickly enough by replacing a deceased motherboard, power supply, or controller, but component failure can have other side effects, especially in disk subsystems where errant or incomplete writes may corrupt boot information and filesystems. The true twilight zone for system administrators occurs when an otherwise useful system is unbootable due to disk corruption or accidental system misconfiguration--your data is just a few inches away, but is inaccessible for one reason or another.



The easiest solution to this sort of problem is a bootable disk known as a "rescue disk," located on removable media such as a floppy disk or CD. These are designed to help you boot failed systems, resolve or work around common problems, and quickly restore your system to self-sufficiency.

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