[Beowulf] Are disk MTBF ratings at all useful?

Joe Landman landman at scalableinformatics.com
Fri Apr 19 17:27:17 PDT 2013


On 04/19/2013 07:38 PM, mathog wrote:
> Joe Landman <landman at scalableinformatics.com> wrote

[...]

> Unfortunately the MTBF is nonsense because the AFR will not
> stay at 0.63%, and most likely would not be measured at 0.63% at

Ask a vendor what their AFR measurements are.  They aren't 0.63%.

[...]

> the spec.  Hard to say because the disk spec sheets do not actually
> disclose
> where the AFR number came from, and few people keep disks that long.
>

We see 2-4% on the good drives, 5+ on the bad ones.  This is from our 
return data.  Typically 1 drive death per 25-50 drives, per year.

> The ratings I would really like the industry to use might be called
> ef1, ef5, and ef10, where each  is the percent of disks that are

Look at AFR from vendor returns.  Not from the manufacturer.



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Joseph Landman, Ph.D
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Scalable Informatics, Inc.
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