Tape Rotation Services

Because of the intrinsic value of data to modern industry, scientific approaches have intersected with technology development and security execution to invent a plurality of data backup schemes and magnetic data tape rotation schedules, intended to provide complete back-ups of pertinent data for the cycle period while balancing data security and the significant cost of backup media and backup media storage to various companies. The amount of effort and the amount of value which pass through these backup systems is so significant that failing to select the proper scheme or consider your way through it can be disastrous, resulting in data loss, data breach, or huge amounts of wasted time and resources.

Among the more prominent data rotation cycles are the Weighted Random System, Incremental Media Method, and G-F-S system.

The weighted random system is designed to achieve, by probability, a random uniform distribution of backup files over time. Backups are made daily (or by whatever micro-cycle your system implements) and each backup, except the first and the oldest, is assigned a probability of deletion of (usually) the square of the multiplicative inverse of days between the date of that backup and the backup before it. By increasing the exponent, over time, this system results in an even continuum of records going back into time. The smaller exponent is useful, however, for keeping a larger percent of more recent generations.

The Incremental media method, on the other hand, is great for keeping the amount of wear and tear on your tapes even over time. The tapes are numbered and rotated until the end of the month (or whatever cycle). The first tape, at the end of the month, is then retired and the tapes, plus one, are cycled again. Thus you slowly add fresh media to the system while keeping a complete permanent archive.

The G-F-S system, which is most used, is similar in many respects. The son tapes are used daily, and at the end of the cycle another type becomes the father—receiving the full weekly backup. The fathers are cycled though as well, and at the end of the month the grandfathers receive a full monthly backup and so on until a point is reached in which the backups are no longer rotated, but are kept off-site as permanent archives.