Thursday, March 1, 2007

Disk Storage Myth Busters

Interesting myth-busting synopsis on disk drive technologies entitled: "Everything You Know About Disks Is Wrong" over at StorageMojo. Some of the key myths busted by extensive research at Google and CMU include:

  • Disk drives have a field failure rate 2 to 4 times greater than shown in vendors specs.

  • Reliability of both cheap and expensive drives is comparable.

  • Disk drive failures are highly correlated, thus violating one of the assumptions behind RAID Level-5.

  • Disk drive failure rates rise steadily with age rather than following the so-called bathtub function.

Storage vendors such as NetApp and EMC have responded. David Morgenstern asks in eWeek, why would anyone have trusted the MTBFs that appear in vendor glossies in the first place?

Background on failure rate analysis can be found in Chapter 1 of my Perl::PDQ book entitled: Time - The Zeroth Performance Metric.

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