A backup copy is useless if it is destroyed in the crisis, too. Many major computing installations rent warehouse space some distance from the computing system, far enough away that a crisis is not likely to affect the offsite location at the same time. As a backup is completed, it is transported to the backup site. Keeping a backup version separate from the actual system reduces the risk of its loss. Similarly, the paper trail is also stored somewhere other than at the main computing facility.
Personal computer users concerned with integrity can take home a copy of important disks as protection or send a copy to a friend in another city. If both secrecy and integrity are important, a bank vault, or even a secure storage place in another part of the same building can be used. The worst place to store a backup copy is where it usually is stored: right next to the machine.