Storage TCO study "like comparing apples with oranges"

By Stuart Finlayson

Nov 03, 2004: In evaluating the total cost of ownership (TCO) of a storage purchase, it is important to factor in all related costs, but to directly compare a disk storage system with a tape system is like comparing "apples with oranges."

That was the reaction of Gartner's Asia Pacific research director, Phil Sargeant to a study by the Tape Technology Council on the factors that contribute to the TCO of data storage systems.

"Many storage system purchasers focus their attention on up-front costs such as hardware and media costs, installation, controllers, and application software to arrive at a comparative cost-per-gigabyte," said Tape Council president Rich Harada. "Although this cost is a good starting point for any system comparison, it's certainly not the full picture. By examining other factors that can play a role in the long term, the true advantages of one system over another become clear."

According to Harada, some of the commonly overlooked costs include power and cooling, floor space, security, scalability, reliability and personnel training.

Gartner's Sargeant agrees that such costs are important to consider when evaluating a potential purchase.

"You must try to include all the costs associated with purchasing any sort of equipment, whether it's PCs or a large storage system. For example, unless you include things like space and heat, if you have something that is the size of a room and took lots of power to drive it, the cost of that is a lot more than something that sits in the corner doing the same thing that runs on the smell of an oily rag. Other factors such as training, capital costs and migration must be included, as that is the only way you can make direct comparisons."

Where Sargeant takes issue with the Tape Council (a non-profit organisation comprised of tape vendors including Fujifilm, IBM, Imation, Maxell, Quantum, Sony, StorageTek and TDK) is the direct cost comparison the study makes between disk and tape storage systems, when they perform very different tasks.

"We look at comparisons between disk solutions or tape solutions but we don't compare disk to tape, as that is a little bit unfair. Most large organisations have a combination of both anyway – they are likely to have a very big disk infrastructure back-ended with a tape library. It's almost impossible to compare the two. The storing of data on tape is a different argument to the storing of data on disk. Whilst it might be much cheaper to store on tape, it is not comparing apples to apples, because you have to restore data on tape, whereas information is available on disk without having to restore it, so it is very hard to make a comparison with such different devices."

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