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[filmscanners] RE: HD failure [was RE: keeping the 16bit scans}

I agree; it also refers to a sample population as a whole or at large
and not to individual hard drives.  Thus, one cannot on the basis of the
data say what particular hard drive will fail or when it will fail.  The
same goes for the "start/stop" data; it refers to a general sample
population and not to individual drives.  To make any such inferences
from the statistical data to particular individual drives is to commit
what is know as the ecological fallacy.

filmscanners_owner@halftone.co.uk <> wrote:
> Subject: [filmscanners] RE: HD failure [was RE: keeping the 16bit
> scans}
> A mean time between failure of 300,000 hours does not mean one
> failure every 34 years.
> The MTBF refers to the entire population of hard drives. i.e. if
> there are 300,000 drives in use then every hour (on average) one of
> the drives will fail.
> -----Original Message-----
> From: Mike Brown [mailto:mike.brown@mindblown.com]
> Sent: Sunday, March 30, 2003 4:45 PM
> To: KAPETAC@polaroid.com
> Subject: [filmscanners] RE: HD failure [was RE: keeping the 16bit
> scans}
> In the intersts of keeping an interesting thread going here are some
> typical reliability figures for hard drives:
> Mean time Between Failure 300,000 hours (ie one failure every 34
> years)
> Start/stops (at 40 deg C) 40,000
> On the basis of those figures I turned HD power management off on my
> PC. I was finding the disks were getting turned off maybe twenty
> times a day, which equates to one failure every 5 years or so.
> Best regards
> Mike Brown
>> -----Original Message-----
>> From: filmscanners_owner@halftone.co.uk
>> [mailto:filmscanners_owner@halftone.co.uk]On Behalf Of Bob Frost
>> Sent: 30 March 2003 10:57 To: mike.brown@mindblown.com
>> Subject: [filmscanners] Re: HD failure [was RE: keeping the 16bit
>> scans}
>> Laurie,
>> Have you or anyone else seen data for MTBF due to recycling and MTBF
>> due to bearing or other failure? Presumably the manufacturers must
>> know how many startups/downs their drives will survive and how long
>> the bearings will last. If we had that info we could balance one
>> against the other and see where the optimum lies.
>> Bob Frost.
>> ----- Original Message -----
>> From: "LAURIE SOLOMON" <laurie@advancenet.net>
>> To: <bob@frost.name>
>> Sent: Sunday, March 30, 2003 6:30 AM
>> Subject: [filmscanners] RE: keeping the 16bit scans
>>  When I say that turning a HD on and off has a negative
>> effect in terms of wear and tear similar to that which might take
>> place if one left the HD on all the time, I am speaking on the
>> average and not to any particular individual case.  Unless, you are
>> prepared to say that turning a HD on and off does not contribute to
>> its wear and tear, the fact that you personally only do so once a
>> week is sort of irrelevant as a refutation of my point. If you
>> backed up or archived once a day every day, woulod you still be able
>> to clain that the wear and tear of turning the drive on and off is
>> less than keeping it on all the time during that week?
>> -

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