The Infrastruggle

The Persistence of Tape

Even with all the cutting-edge storage technologies, one of the original methods is still viable.

• By Jon William Toigo
• 03/16/2017

Magnetic tape storage predates the flash and disk storage platforms that dominate most discussions of contemporary data storage infrastructure in the technology trade press, and at trade shows and conferences. Despite its role as an anchor technology for reliable data storage, especially in larger firms and large cloud service provider shops, tape has been steadily losing mindshare among smaller and medium-sized firms in recent years.

This may be in part the result of a loss of "generational knowledge." College students in information technology degree programs as well as novice practitioners in certification and training programs report that tape has never been mentioned in their classrooms.

Of course, there are other explanations for the limited information many IT professionals possess about tape, including years of neglect by the tape industry in responding to numerous pessimistic reports about future of their technology, and hazy recollections about the foibles of tape technology itself and of the applications that use it.

The 'Rule of Thumb' That Never Was
A disproportionate number of IT professionals still recall a statement from the late 1990s that industry analyst Gartner denies ever having made, to the effect that 1 in 10 backup tapes fail on restore. This was never the case, but it was a statement repeated often enough and with attribution to Gartner that it became a "rule of thumb."

Yet, despite the many hurdles, tape persists -- and in all three of its original roles. In some firms, tape continues to deliver value as a production storage medium -- that is, as the first place where data is written. Evidence can be found in numerous particle physics and genetics research labs, and even in some movie production companies. The main reason is low cost and high capacity, but tape is also a very fast write target and an almost jitter-free read source whose streaming (data transfer) rate has only recently been rivaled by the most expensive NVMe flash storage.

Cheap, Durable, Portable
Secondly, tape continues to provide backup services, a role to which it is well-suited, not only for cost and capacity reasons, but also because of tape's portability, resiliency and durability. Only high-end flash boasts a bit error rate as low as tape or posits a durability metric that approaches tape's 30-year lifespan -- but it does that at several hundred times the per-GB cost of tape.

Durability also contributes to tape's ascending role in archival storage today. Plus, as an inherently green technology, tape presents extremely low energy consumption characteristics, making it the darling for energy-constrained data centers that must nonetheless store large volumes of data in a manner that's Web accessible for governmental regulators (e.g., pharmaceutical companies in power grid-saturated locations in the New England Corridor).

Still, despite the persistence of tape, repeated surveys of smaller firms suggest that tape is hardly being deployed, and those who have tape are seeking to remove it from service. Reasons cited include a lack of staff or skills to operate tape systems and processes; the manual nature of tape operations; and the lack of support for tape in popular server hypervisors and operating systems.

Just the Facts
Some small firms claim that online backup and cloud storage services provide a better data protection or archiving approach, given their budget, staff levels and other capabilities. However, there are some facts that may not be clear to IT planners in small and medium shops that should be considered in storage planning:

• Contemporary tape is the only technology poised to dramatically increase in capacity within the next three years. 3D flash is increasing capacity by stacking bits in vertical layers, but the cost and performance metrics of this storage modality is subject to much debate. Heat-assisted magnetic recording (HAMR) is supposed to be the next big thing for disk, getting us beyond the hard limits to perpendicular magnetic recording that kept disk capacities growing for the past five years, but it's proving more difficult than anticipated to deliver as an affordable, reliable storage technology. Optical disk is woefully lacking in capacity, and write speeds are abysmal. So, with zettabyte-sized data growth on the horizon, only the capacity of tape, enhanced by Barium Ferrite media coatings, will see firms through the forthcoming data deluge.

• The Linear Tape File System (LTFS), an IBM innovation that became an ISO standard last year, enables file system- or object system-based data to be copied directly to tape media, much in the manner of a USB drive. Once recorded on the tape cartridge using LTFS, data is "self-describing" -- that is, the data can be read directly by any server or application, without the need for specialized software. LTFS is a bridge that enables the proprietary containers used by backup software and some archive software products to be relegated to the dustbin of history. So, if the reason for replacing tape is the complexity of the backup software, problem solved.

• Finally, the nature of data itself should be considered. Most data today consist of files and objects that are re-referenced frequently shortly after creation, then never consulted again. Instead of filling up the expensive capacity of flash or disk arrays with data that's rarely accessed or modified, migrating that data to tape and freeing up expensive capacity makes a lot more sense. In fact, large technology vendors have begun talking about topologies such as FLAPE, in which data is written to both flash and tape, then deleted from flash after re-reference rates fall.

Not Going Anywhere
Bottom line: even smaller firms can benefit from tape storage; in some cases for production storage, but most certainly for backup and archive. Those who seek to replace tape with cloud services or storage may have a valid case to make, but they may be surprised to learn how many cloud service providers are, in fact, using tape to store the data they're being sent.