Disk vs. Tape: Tape is Unbowed

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For the past five years or more, articles have been appearing about the death of tape. virtual tape libraries (VTLs) and other disk-based backup strategies have been held up as more efficient, faster and so on. The rise of deduplicationseemed to reinforce this message by making it possible to pack around 20 times more backup data onto disk.

Certainly, tape has lost a lot of ground to disk, particularly at the lower end of the market, and as a repository for recent backup data. Like a tenacious tenant who refuses to be evicted from an area earmarked for redevelopment, tape is alive and kicking. And for long-term backup retention and archiving, tape appears to be holding its own — especially among large enterprises.

This was brought home recently vendors Quantum and Spectra Logic approached ServerWatch for pre-briefs on their latest tape offerings. PR agencies and vendors expending effort to develop, manufacture and market brand new tape libraries? They wouldn’t be doing it if they couldn’t turn a profit with these products. And they can.

How are tape sales? IDC references several studies. Tape overall is down, although the slide is mainly at the lower end. Robert Amatruda, a tape analyst for IDC, said that the market for tape automation products below 100 tape cartridges would suffer most. Another IDC study on Asia-Pacific sales from last year showed automated tape libraries to be up 15 percent for the year, while tape drives fell 19 percent. Cheryl Ganesan-Lim, an IDC analyst, noted that disk storage allows better recovery speeds, thus making it suitable for Tier 1 and Tier 2 storage. Tape, on the other hand, is better for deep archiving of rarely accessed data. She expected tape library sales to rise slightly over the next five years.

So tape is down in lower-end, smaller-scale and more immediate data recovery categories, but it is largely holding its own at the high end. It looks like tape’s death isn’t imminent.

Why Tape Hangs On

So why hasn’t tape quietly faded away? Molly Rector, vice president of marketing and product management at Spectra Logic, stated the one fact that disk vendors just can’t defend. Tape is much less expensive. She agreed with the IDC view that tape’s role is to function as part of a tiered infrastructure in which it is used for archiving.

“We are seeing growth in sales in our tape products,” said Rector.

Accordingly, the company just rolled out its latest and greatest. The Spectra Logic T-Finity enterprise tape library comes with multiple, redundant robots and can scale to 45 petabytes (180 PB by combining four boxes into a unified library complex). Rector boasts that this offers the highest storage density available today — 72 TB per square foot — and it scales to more than 30,000 slots in one library. In terms of power efficiency, she reckons it destroys the competition. One slide indicated the T-Finity toasts the IBM TS3500 and the Sun STK SL8500 on watts per TB and overall heat dissipation.

Read the rest at ServerWatch.