Don?t be duped by de-dupe ratios

Posted on February 01, 2009

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Dave Simpson

Editor-in-chief

In these belt-tightening times, “asset optimization” technologies, such as data compression, virtualization, thin provisioning, automated tiered storage and, perhaps most of all, data de-duplication, will be increasingly adopted by IT managers who need to “do more with less.” But in the case of data de-duplication, some vendors’ wacky claims regarding de-dupe ratios have led to inflated expectations in the user community.

The Special Report on page 15, “Understanding data de-duplication ratios,” (which was written by representatives from the Storage Networking Industry Association) sheds some light on this topic, and draws conclusions grouped under three assumptions:

  • Relatively low de-duplication ratios can yield significant space savings. (“De-duplication ratios of 50:1 and 500:1 yield an incremental 8% and 9.8% disk savings, respectively, beyond the 90% disk savings achieved with a 10:1 de-duplication ratio,” according to the article.)
  • Ratios are meaningful only when compared under the same set of assumptions. (For example, is the data temporal or spatial?)
  • De-duplication ratios are influenced by the characteristics of the data. (This includes the length of time that data is retained, the scope of the data de-duplication, type of data, frequency with which data is changed, and other factors.)

Also in this issue . . .

In a recent InfoStor QuickVote poll of our site visitors, 9.8% of the respondents said they were currently using solid-state disk (SSD) drives, while another 26.3% said they planned to use SSDs within the next year. But 63.9% said they had no plans to use SSDs. Nevertheless, virtually every storage industry analyst puts SSDs on their list of top technologies for 2009.

In “Who uses SSDs, and why?,” (page 18) Objective Analysis’ Jim Handy explains that flash-based SSDs will be hot in the budget PC and enterprise server markets, but that they are unlikely to gain much acceptance in the notebook and desktop PC markets. He also predicts that the enterprise-class SSD market will top $1 billion by 2013.

In “FCIA makes the case for FCoE,” (page 24) representatives from the (not unbiased) Fibre Channel Industry Association shine a positive light on the controversial Fibre Channel over Ethernet standard.

In our next issue, an industry analyst will tackle the FCoE controversy.


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