Part 2: Why Tape Rolls On: Green Storage

Reading time for this article .

It’s been said that airplanes magically turn money into noise.  In a similar way, it can be stated that disk storage turns money into heat.  In both cases, benefits like fast, reliable transportation and fast random data access accrue as the result of said magic.  Unfortunately, it also means a LOT of money may be involved yielding a lot of noise and heat respectively.

Setting aside the airplane analogy to concentrate on the conversion of money into heat through spinning disk over the long run, what can a storage administrator or CIO due to mitigate the cost of this magical transformation?  The answer to reducing the budget in various cases is tape storage.

Over the past four years, The Clipper Group has conducted a number of studies investigating the cost of disk and tape, including comparisons of power consumption.

The 2007 Clipper paper, “Tape and Disk Costs – What it Really Costs to Power the Devices” looked at a 5-year cost comparison between the power consumption of tape and that of SATA disk and concluded that, “The disk system costs over 25 times more money to power and cool than a similar tape system.”

In February of 2008, Clipper published, “Disk and Tape Square off Again – Tape Remains King of the Hill with LTO4”. In this case, Clipper investigated the 5-year cost of a tape backup system relative to that of a disk-to-disk backup system over the same period.  Clipper’s conclusion: “The energy cost ratio for a terabyte stored long-term on SATA disk versus LTO-4 is about 290:1.” 

Last December (2010), Clipper published their latest analysis, “In Search of the Long-Term Archiving Solution – Tape Delivers Significant TCO Over Disk.” In this instance, Clipper looked at a 12-year time horizon for both disk and tape systems and concluded the following, “The cost of energy alone for the average disk based solution exceeds the entire TCO of the average tape based solution.”  More specifically, “…disk consumes 238 times as much energy as tape under assumptions that lean toward favoring disk.”

With the average price per kWh consumed having increased by 33% over the past 10 years (Source: U.S. Energy Information Administration) holding data long-term is likely to become a relatively expensive energy proposition – especially if you try to retain all that data on disk.  If you project out the amount of data that may be stored, as the Enterprise Strategy Group has done (Spectra Blog: What could you buy for the cost to power an archive?), you can get a sense of what it might cost to power all that storage on either disk or tape.

The economics of tape energy consumption make it an ideal long-term storage repository.  Could that be Why Tape Rolls On?

To learn more about Why Tape Rolls On, see part one of this series discussing the Security characteristics of tape.