Tape is low cost and a low carbon storage winner

Consultant Brad Johns thinks moving archive data from disk to a 60:40 tape:disk situation could cut its ten-year CO2 emissions by almost 60 percent and its total cost of ownership by almost half.

Update: Critical point of view about tape infrastructure exclusion from tape numbers added. 12 July 2022.

Johns presented his findings at the Fujifilm 12th Annual Global IT Executive Summit in San Diego, June 22–25. He worked out the CO2 emissions and TCO numbers using three scenarios for storing 100PB of data for ten years: all disk storage, 60 percent tape and 40 percent disk, and all tape. The numbers were based on amounts provided by Seagate of its 18TB Exos nearline disk drive and Fujifilm for its LT0-9 tape cartridge with 18TB of raw capacity. 

His worked out CO2 numbers only includes the estimated CO2 impact of the storage media. They exclude controllers, networking, tape libraries, tape drives (except energy), cooling and electrical systems. A chart shows the  CO2 emission findings: 

The 60:40 tape:disk setup puts out 1,1134 tons of CO2 whereas an all-disk equivalent emits 2,663 tons – 42 percent more. An all-tape system outputs 79 tons – 97 percent less than the all-disk configuration. 

Supercomputing expert Glenn Lockwood tweeted about the exclusion of controllers, networking, tape libraries, etc: “Disingenuous; tape has a much higher barrier to entry (robotics, drives, etc) than HDD which wasn’t included. Nor was cooling; can’t run tape without climate control (dew point), but you can run disk.”

The Fujifilm and Johns thinking is that CO2 emission data will play an increasingly important part in customers’ IT purchase decisions as ESG (Environmental, Social and Governance) reporting becomes more widespread and organisations will want to demonstrate progress against ESG goals.

The cost findings are quite persuasive as well:

  • All disk – $17,707,468
  • 60:40 tape:disk – $9,476,339 (46 percent less than all-disk)
  • All tape – $3,832,956 (78 percent less than all-disk)

Johns calculates that moving 60 percent of the world’s HDD-resident data to tape would save over 72 million tons of CO2e. Much of the data currently on hard disk drives is, he says, cold data and could be more cost-effectively stored on tape where it would emit less CO2 as well.

We could ask if storing all this data is worthwhile in the first place, as it costs so much money and contributes to global warning. Suppliers of storage media and their contracted consultants don’t ask such questions, focusing instead on the merits of their respective media. In this case it’s tape good and disk bad. 

A Fujifilm and IBM-sponsored white paper written by Johns states: “Given the focus on sustainability and the large volumes of storage devices required to store the growing quantities of data in the coming years, organizations have an opportunity to reduce their carbon footprint, improve sustainability and reduce expenses by migrating less frequently accessed (cold data) from shared disk drive (HDD) based storage to modern tape storage.“”

Note the snarky use of the term “modern” here by Johns in describing tape storage. Is he trying to say that disk drive storage is not modern? That would be a ridiculous stance to take – an 18TB disk drive is every bit as modern as an 18TB tape cartridge.