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Vol. 7 No. 8 October 2008

Compression puts the squeeze on dedupe

DEDUPLICATION IS ALL the rage these days, while the good old-fashioned Lempel-Ziv (LZ) compression technology we all grew up with is taken for granted. The real differences between dedupe and compression have to do with algorithms or how each one does its job. But not many of us need to know algorithm differentials to do our jobs. "I think there's a lot of confusion in the marketplace," says Arun Taneja, founder and consulting analyst at Taneja Group in Hopkinton, MA. "Most people aren't computer scientists." Both technologies shrink data volumes. Compression does it by squeezing out repetitive bits in a data stream, cleaning redundant data within a file. Dedupe compares objects at the file and sub-file level, removes duplicate files by referencing the original and saves only one instance. Standard compression technology provides about a 2:1 ratio, halving the number of bits in a stream. Both tape and disk can accommodate compression. Dedupe, which is strictly for disks (tape can't accommodate its serial nature), boasts ratios ...

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Features in this issue

  • Are solid-state disks ready for the enterprise?

  • Green spin cycle

  • Second-generation CDP

    Continuous data protection (CDP) received lots of attention but garnered few takers as a standalone product. Since then, the technology has been incorporated into data protection products and its role is now likely to expand. In addition, rapid data growth and shrinking backup windows are two of the trends that support the increased adoption of CDP.

  • Solid-state distinctions emerge

  • Economy and capacity at odds

    With fewer bucks in the budget, storage managers are facing some constraints in dealing with growing storage capacities. But, according to Storage magazine's Purchasing Intentions survey, they're responding by earmarking some of those dollars to newer technologies like data deduplication that will help them cope with burgeoning data stores.

  • The green storage gap

    by  Ellen O'Brien

    Storage departments are trying energy-saving technologies, but measuring ROI is still a challenge. Some storage administrators are plugging vendor-supplied product power consumption numbers into so-called green calculators, but it's no easy task as there are inconsistencies in how each vendor presents its product's power requirements.

  • Storage for high-performance computing

    by  Deni Connor

    The storage and server cluster installed at The University of Texas at Austin is a lesson in how to do high-performance computing (HPC). Storage requirements for HPC go beyond massive capacity and include the use of high-performance file systems.

  • Ask the Experts

    Where and when should we use data dedupe for remote-office backups?

Columns in this issue

  • Best Practices: Why you can't go it alone

    by  Ashish Nadkarni

    Most IT departments are split into islands of expertise, like storage, servers and networks. But the time is coming when those disparate groups will have to learn to work together. Network consolidation is just one of the technologies forcing storage pros to build stronger interdisciplinary IT teams.