Page 1329 - (ISC)² CISSP Certified Information Systems Security Professional Official Study Guide

period. Murphy’s law dictates that a server never crashes immediately
after a successful backup. Instead, it is always just before the next

backup begins. To avoid the problem with periods, you need to deploy
some form of real-time continuous backup, such as RAID, clustering,
or server mirroring.

Finally, remember to test your organization’s recovery processes.
Organizations often rely on the fact that their backup software reports
a successful backup and fail to attempt recovery until it’s too late to

detect a problem. This is one of the biggest causes of backup failures.

Tape Rotation

There are several commonly used tape rotation strategies for backups:
the Grandfather-Father-Son (GFS) strategy, the Tower of Hanoi
strategy, and the Six Cartridge Weekly Backup strategy. These
strategies can be fairly complex, especially with large tape sets. They
can be implemented manually using a pencil and a calendar or
automatically by using either commercial backup software or a fully

automated hierarchical storage management (HSM) system. An HSM
system is an automated robotic backup jukebox consisting of 32 or 64
optical or tape backup devices. All the drive elements within an HSM
system are configured as a single drive array (a bit like RAID).

Details about various tape rotations are beyond the scope

of this book, but if you want to learn more about them, search by
their names on the internet.

Software Escrow Arrangements

A software escrow arrangement is a unique tool used to protect a

company against the failure of a software developer to provide
adequate support for its products or against the possibility that the
developer will go out of business and no technical support will be
available for the product.