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Tape Rotation Schedules That Work

There are a lot of poor or risky data tape rotation schedules that businesses routinely employ, but throughout all of the trial and error brought on by the onset of the digital age a number of tried and true systems have also emerged as defacto best practices. Certain traits, such as daily backups, offsite storage, and long term capabilities have grown to be important factors in deciding which schedules are most effective for almost all companies and situations. In general, three systems have grown into common use: the Grandfather-Father-Son system, the Tower of Hanoi system, and Daily + N Weekly system.

The most versatile and well known of the three is the Grandfather-Father-Son tape rotation schedule, which uses three tiers of backups to protect the continuity of the data. Son tapes are the day-to-day tapes recorded Monday through Thursday and recycled each week. Father tapes are weekly backups recorded each Friday and reused each month, and Grandfather tapes are recorded on the last Friday of the month and reused each year. This system uses approximately 20 tapes, and combines onsite and offsite data storage.

The Daily + N Weekly system uses a large number of tapes to take daily backups, similar to a Round Robin schedule. Every few weeks (N) the tapes are recycled back into circulation, with the exception of one tape a week that is archived to provide a weekly backup. This can be a cumbersome rotation system, but it is effective and often used by smaller businesses.

The Tower of Hanoi is the most complex rotation schedule, but is a recursive method that uses the least number of tapes. At least 3 tapes must be used for this system to work, and each additional tape will double the number of days in the rotation cycle. This schedule works by using Tape 1 every other day, and rotating Tapes 2 and 3 every day in between. For example, Day 1 uses Tape 1, Day 2 uses Tape 2, Day 3 uses Tape 1, Day 4 uses Tape 3, Day 5 uses Tape 1, Day 6 uses Tape 2, and so on. When using additional tapes this system provides daily and monthly backups using far fewer tapes than the other schedules, but is very complex and not always supported by backup software.