Any organization that works with mission critical or otherwise sensitive data should have an efficient data backup system in place. While a simple backup plan might suffice for smaller companies, larger organizations require something more complex. For those who still use data backup tape, this comes down to choosing the right data backup rotation scheme.

Round Robin
Round Robin One of the simplest backup tape rotation schemes, the Round Robin method relies on the backup administrator to decide the retention period for each tape. A separate tape is used for each day until the final date of the retention period is reached - at which point the tapes are re-used, in the same order, and the whole process is repeated. This ensures that each backup remains available for the same amount of time.

Unfortunately, the Round Robin method doesn't accommodate long-term data archival. As a result, many organizations choose to modify this scheme by holding certain backup tapes for longer than the standard retention period. For example, every fourth tape might be held and preserved as a monthly or even quarterly backup.

N Week Daily
A popular alternative to the Round Robin rotation scheme, N Week Daily (where N equals the specific number of weeks) essentially reduces the amount of physical backup tapes needed on a weekly basis. It utilizes a one-week rotation cycle that removes one tape from the cycle each week. This tape is then held as a weekly backup. After a certain number of weeks has passed (specified in the N variable), the weekly tapes are introduced back into the tape rotation scheme and used as normal.

First In, First Out (FIFO)
This method ensures that the newest and most recent files are always saved on the oldest tape available, thus creating a cycle that is constantly rewriting old, outdated data with new, updated data. In this scheme, the length of your backup timeline is ultimately dictated by the number of tapes that are being used.

Grandfather-Father-Son (GFS)
Similar to the FIFO method, the GFS rotation scheme is commonly used when multiple data backup cycles are in use - such as weekly, monthly, and quarterly backups. Other than that, the GFS scheme mirrors the FIFO method by saving the newest and most recent files to the oldest tapes available.

Tower of Hanoi
One of the most complicated data backup rotation schemes available, the Tower of Hanoi method is based on a mathematical puzzle that dates all the way back to 1883. This rotation scheme works by exponentially increasing the retention period within a recursive pattern. If four tapes are used, for example, the first tape is backed up every two days, the second tape is backed up every four days, and the third and fourth tapes are backed up every eight days. In this scenario, the overall data retention period is eight days - despite the fact that only four separate tapes are used.

Finding the Rotation Scheme That's Right for You
With so many different rotation schemes available, it can be difficult to find the perfect one. Larger organizations will likely opt for Round Robin or N Week Daily, but there are exceptions. Conversely, those who are operating on a budget will likely prefer the Tower of Hanoi method. They're all viable solutions and there's no right or wrong answer - it all comes down to your specific needs, objectives, and preferences.