This is really a tough question to answer, because there are so many different factors involved. Although the manufacturer might recommend certain durability ratings, these will vary based on how you use the tapes.
For example, a typical “Linear Tape-Open” (LTO) tape might be rated for 5000 cartridge loads, 250 full tape passes, and 15-30 years of storage.
- If you only fill your tapes to partial capacity, you can extend the number of tape passes significantly.
- If you store the tapes in an environment where the humidity and temperature vary greatly, this can shorten the lifespan of the cartridge.
- If your backup software goes back over your tape to check for errors after every write process, this will count as 2 full tape passes for each backup. You’d have to divide your total maximum passes by half.
As you can see, maintaining the integrity of your archival storage isn’t easy. Here’s a possible solution that I might recommend.
For the best results, you should be creating copies of all your archival data every 1-2 years. Of course, this isn’t ideal for very large organizations. So in order to minimize the work, I’d suggest implementing a deletion/retention policy that allows you to keep the minimum possible amount of data without violating any compliance rules. This should make the process much faster and easier.
Another approach would be to make 2 copies of each backup tape, and have them stored in 2 different locations. And of course, each should be kept in humidity/temperature controlled environments as suggested by the manufacturer.
If your company is charged with protecting large amounts of highly critical data, I’d suggest having a conservative disaster recovery plan that works well within the limits and constraints suggested by the manufacturer.
This way, you’ll be well within the safety limits for your data storage.