At most sites, the information stored on computers is worth far more than the computers themselves. It is also much harder to replace. Protecting this information is one of the system administrator’s most important (and, unfortunately, most tedious) tasks.
There are hundreds of creative and not-so-creative ways to lose data. Software bugs routinely corrupt documents. Users accidentally delete data files. Hackers and disgruntled employees erase disks. Hardware problems and natural disasters take out entire machine rooms.
If executed correctly, backups allow an administrator to restore a filesystem (or any portion of a filesystem) to ...