The ABCs of CDP

As you read this, we’re probably sweating it out in Orlando at the semi-annual Storage Networking World extravaganza. It was one year ago, at the last SNW Fall show, that so-called continuous data protection (CDP) leapt into the top-five storage buzzwords.

Although it’s still unclear whether users will jump on this buzzword bandwagon, we decided to go overboard in this issue with two cover stories and two feature-length articles on this topic.

The two cover stories deal with the entry of Symantec and IBM into the CDP market. We covered Microsoft’s “near-CDP” Data Protection Manager on the cover of our August issue (see “Microsoft enters D2D backup market”).

Until Microsoft, IBM, and Symantec entered this space (and EMC is expected to enter soon), the CDP market consisted of about a dozen relatively unknown players, many of which were start-ups. And end-user adoption was minimal, in part because some of the early CDP products were very expensive. But the products from Microsoft, IBM, and Symantec are all less than $1,000 so I think it’s safe to bet that this market will take off rapidly around the turn of the year.

In addition to our cover stories, be sure to check out “Continuous data protection: Is it about time?”, by Mark Ferelli and David Freund, and “Evaluating continuous data protection,” by Dianne McAdam (pp. 28 and 32, respectively).

Most analysts think that CDP is poised for takeoff, but there is still debate about the definition of CDP, not to mention “true CDP” vs. “near CDP,” “constant” vs. “periodic,” etc. Not surprisingly, the Storage Networking Industry Association (www.snia.org) has formed a group to address CDP. (For SNIA’s take on the technology, see “CDP: What it is, and why you need it,” InfoStor, September 2005, p. 42.)

CDP is a subset of a much larger trend: disk-to-disk backup and recovery, which has been made possible in part by low-cost, high-capacity Serial ATA (SATA) disk drives. According to a poll of our readers, more than half said that SATA will account for the majority of their non-desktop drive purchases over the next six months (see pie chart).

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What’s interesting is that the emerging Serial Attached SCSI (SAS) disk interface is starting to show up in polls of this sort, even though it’s available from only a few server vendors (most notably, Hewlett-Packard). In the InfoStor survey, 11% of our readers said that SAS will account for the majority of their drive purchases over the next six months. Although SAS (which also supports SATA) is designed primarily as an in-the-box, DAS interface, it could also, theoretically, be used to build mini-SANs. To explore this curious notion, read Kevin Komiega’s “Do SAS-based SANs make sense?”, p. 8.

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Dave Simpson

This article was originally published on October 01, 2005