Long-term Archive Media Costs

While it may be seductive to look at the cost of media as a finite set of numbers for a specific component of storage and retrieval activities, that approach does not begin to answer questions about system costs and reliability to accomplish the goals of maintaining image data files over decades.

At face value, tape appears to be the least expensive alternative for long-term archiving of images and patient data. But when considerations such as the total costs of ownership that include re-tensioning tapes, establishing a space to store the media, maintaining a dust-free environment because dust destroys tapes, and the time expenditures in finding the correct study stored in that manner come into play, the least expensive option does not emerge as the most appealing.

John Quinn, principal and CTO for Capgemini Health, explains that there will be a burgeoning storage issue over the next five years or so in regards to the amount of information that is being maintained, and the legal implications of those activities. One driving force in healthcare is to reduce the number of personnel necessary to accomplish specific tasks, so the more automated the storage system, the better it is perceived to be - regardless of cost.

Deniese Chaney, senior manager in healthcare products for Capgemini Health in Atlanta, notes that the cost of media continues to decline rapidly, and that as spinning disk media is developed with higher levels of density at a comparable or lower price than the former generation, the net result is a reduction in expenditure for the media component of storage systems.

Additionally, Chaney notes that a phenomenon is occurring in the PACS (picture archiving and communications systems) marketplace, where vendors that submit quotes for storage activity propose totally online storage via storage area networks (SAN) or network attached storage using RAID level five or greater disks. In this scenario, all images are kept online in perpetuity or for as long as the institution chooses to keep them. This non-removable option, while not the focus of this article, suggests a trend none-the-less.


Placing the cost of media in context

These days, industry leaders describe media costs in terms of Total Cost of Ownership (TCO) for an entire archiving solution. This approach considers not only the original acquisition costs for the system, but routine maintenance of both the system and the media, space requirements for the system and storage of removable media, as well as other intangible costs.  Several vendors have calculated TCO matrices that include relative costs for media.

In a recent analysis performed by Plasmon (Inglewood, Colo.), results demonstrated that the total cost of ownership of AIT (Advanced Intelligent Tape), DVD (Digital versatile disc) and the new Plasmon UDO (Ultra Density Optical) archives are very similar and lower than magneto optical when calculated for archival storage of 12 TB (terabyte) over three years. The report reveals that although the numbers collected for this analysis do not incorporate all possible system and operating expenses, they do offer an accurate relative percentage for the selected media products. And they find that contemporary optical technologies such as DVD and UDO, while slightly higher, remain price-competitive with tape.

"When you add everything together, the media costs are dwarfed, but that's what people tend to look at," says Dave Dupont, vice president of marketing and sales for Plasmon. Optical solutions are not as inexpensive as tape, but they are durable. "Eighty percent of the cost involves acquisition costs of hardware and software and maintenance costs for both software and hardware."

Mark H. Wheeler, GM Image Management, Ultrasound Software and IT for GE Healthcare Technologies, selected Plasmon UDO as one of their archiving strategies. He explains that there are three factors that drive decisions around selecting archiving media. For their purposes, cost is the third consideration after reliability within the framework of longevity, and the ability for the system to grow easily.

After careful analysis, he determined that the UDO technology was the most reliable for several reasons. The "write once" approach means the end-user cannot accidentally write over important data. The second reason is that the design of the UDO cartridge is such that it helps to eliminate the dust problem. As systems age, and hospitals undergo building programs, dust becomes a major issue for media functionality. Tape is the most vulnerable to damage from dust.

The third reason they selected UDO over tape is that medical archiving activity requires that a study be written to media once, but read many times.

"As you put multiple exams on a library full of tapes, you actually begin destroying the tapes themselves, unless you put into place a system to re-tension the tapes and cycle old tapes out and replicate them," says Wheeler who notes that most customers don't do that. "You end up with an unreliable system that will 'eat itself alive' fairly quickly." UDO offers much-improved longevity by his assessment.

Wheeler runs the numbers this way. The cost per terabyte of storage after the initial investment ranges from $500 to $600 at $40 for 30 GBs now, which should drop in the future as this media develops to 60 GB capacity. Over the long haul, a department would need to replace drives at some point, which cost about $1,500 apiece. GE offers drives in 1, 2, 4 and 6-drive configurations. Besides the drives, the only additional primary expense is the cost of media, and assuming the media is $50 for 60 GB, an institution could add a terabyte of data storage for about $800.



Esteban Ruben, a storage consultant at FujiFilm Medical Systems USA, says that tape is definitely the least expensive media available. And he explains that the tape of today is much more reliable than that available 15 years ago, where some spectacular failures occurred in facilities that were writing to tape. At this point, if an institution selects tape as their long-term storage option, he recommends that as best practice, they write to at least two copies. 

"You don't want a single point of failure, so you wouldn't write to a single tape," says Ruben. He recommends complete back-up capabilities and an intelligent architecture that takes into account possible failures in tape.  "The technology will be as good as how you implement it." This strategy, while brilliant, requires an institution to purchase twice as much tape for the same storage functionality. Fortunately, LTO (linear tape open) technology has advanced to LTO-2 tapes that hold 200 GB of data, and run close to $0.26 per GB by Ruben's calculation. LTO-3 is on the horizon, for similar costs, and it doubles the capacity to 400 GB native.

Mike Sutherland, vice president of medical division for TDK Electronics Corp., raises another issue. As a supplier of media to OEMs such as GE Healthcare, Siemens Medical Solutions and Philips Medical Systems, TDK began developing medical grade media that has proceeded through the FDA 510(k) approval process for medical devices.

"We build a product that is beyond the Orange Book 2 specification to enable enhanced compatibility and longevity," says Sutherland. They use a pure silver reflective layer to provide stability and combat corrosion, which can increase error rates and cause disks to become unreadable. The dye material they use in their CDs and DVDs is controlled to tight tolerances. "We have accelerated aging tests that suggest that our CDs are rated at 100 years." 

A 10-pack of medical grade CD-R that hold 650 MB of data is priced at $55 according to the TDK website.


Conclusion

The cost of media has become a more complex issue than it might seem on the surface. While price comparisons of specific products may offer some information, the total cost of ownership of a storage system is most revealing about expenditures that will be required.