Tape Rotations
After you have decided on the backup type you will use, you are ready to choose a backup rotation. Several backup rotation strategies are in usesome good, some bad, and some really bad. The most common, and perhaps the best, rotation strategy is the Grandfather, Father, Son rotation (GFS).
The GFS backup rotation is the most widely used and for good reason. An example GFS rotation may require 12 tapes: four tapes for daily backups (son), five tapes for weekly backups (father), and three tapes for monthly backups (grandfather).
Using this rotation schedule, it is possible to recover data from days, weeks, or months previous. Some network administrators choose to add tapes to the monthly rotation to be able to retrieve data even further back, sometimes up to a year. In most organizations, however, data that is a week old is out of date, let alone six months or a year.