By William (Chris) Vest, Sr. Systems Administrator
Linear Tape-Open (LTO) is a super cheap magnetic tape that allows enterprises to store large amounts of data. It’s been around for over two decades and has become a ubiquitous part of enterprise backup strategies. Besides providing a cheap storage media, LTO facilitates the 3-2-1 rule best business practice, and the protection of offline (“Air Gapped”) data storage. But with the advent of cloud storage, broadband networks, and immutable online storage, there are now other ways to accomplish these data protection goals.
Both the value and curse of tape is that the media is separable from the drive and, thus, takes a critical mass of data to break even on its efficiency. As of this writing, the top of the price/size for the media today appears to be the LTO8 at $60 for 12TB (native) or $5/TB. By comparison, LTO9 is still $150 for 18TB (native) or $8.33/TB. Native sizes are used for comparison because compression factors vary greatly depending on the data type. This doesn’t take into consideration the expense of the media library and the drives themselves. Enterprise class fibre channel LTO8 tape drives for media libraries cost about $25K each. The cost of media libraries can vary based on the number of tapes (and drives) they hold, but let’s estimate another $25K for the library. That would bring the cost/TB for a 250TB backup set to approximately $200/TB using 25 tapes. If the library and drive are kept for 5 years, then the annual cost for that drops to ~$40/TB/year. Note: this glosses over all the costs for having a physical facility (electricity, taxes, repairs, insurance, etc.), as well as the costs for offsite storage.
Going to a prominent cloud provider targeting archive class storage, costs are characterized differently. Instead of just the size of the backup set (250TB/Mo), it introduces costs for upload requests (50000), restore requests bulk (50) and standard (100), data retrievals bulk (2TB) and standard (1TB), inbound (5TB) and outbound (3TB) data transfers. This worked out to approximately $14500/year total, or about $58/TB/year. Note: The archive target can be located much further geographically, and possibly still be cheaper.
Changing the requirements can affect these numbers notably, so your milage may vary. It is also important to point out that onsite costs can be notable depending on location, as can data transfer costs, although they were downplayed in this review (because of variability), it can make a difference in your results. Nonetheless, the LTO consortium has made great strides to try to keep tapes a contender through increased density and retention resiliency. They have an aggressive growth strategy to double the capacities for tapes each generation starting with LTO 9 at 18TB, through LTO12 at 144TB all while maintaining the same Ultrium form factor. Tapes can still be a part of the enterprise backup strategy, especially when considering other aspects such as air gapped archives vs immutable online as part of a sound 3-2-1 backup plan.