[Beowulf] Are disk MTBF ratings at all useful?

[mathog]

On 18-Apr-2013 16:03, Alex Chekholko wrote:
> On Thu, Apr 18, 2013 at 4:01 PM, mathog <mathog at caltech.edu> wrote:
>> How do they come up with the MTBF values for disks anyway?  Clearly 
>> it
>> is not based on watching a large
>> sample of disks for countless years!

> How would you do it?

On a brand new design, I have no idea.

On an incremental design, which mechanically is what most disks are, I 
would take into
account the failure rates of the components in the previous generation 
and extrapolate that
to the new design (where possible).  For instance, one could
tear down and carefully examine the moving components to measure the 
wear they suffered
over several years. They could also do "accelerated aging" studies 
(running the drives
under less than ideal conditions). That method is good for testing 
paint, but I would not
have a lot of faith in it for a device as complicated as a disk.

Regards,

David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech