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[filmscanners] RE: HD failure [was RE: keeping the 16bit scans} OT if you don't mind losing your images



>Failure rates typically follow what's known as the bathtub curve.

In other quarters, it is known as a "Normal Curve."

>The number is correct for a single drive,

What do you mean by this.  Yes the number is correct for single drives as
contrasted to RAID Arrays; but it is still based on and describes a
statistical aggragate or population of single drives taken as a sample
universe and not the indivudal members of that universe.

>The main point still holds good - hard disks are most likely to die of
power
>cycle related failures if aggressive power management is in use.

That may be true but it also may not be. the findings you refer to really do
not speak to the point either way.  It could be equally probably that there
are other causes and reasons for had drive failures and maybe even other
reasons besides aggressive power management for power cycle related
failures.  The material presented does not speak to any of this nor does it
tell one what a hard drive is most likely to die from.


-----Original Message-----
From: filmscanners_owner@halftone.co.uk
[mailto:filmscanners_owner@halftone.co.uk]On Behalf Of Mike Brown
Sent: Monday, March 31, 2003 4:30 PM
To: laurie@advancenet.net
Subject: [filmscanners] RE: HD failure [was RE: keeping the 16bit scans}
OT if you don't mind losing your images


Constantine

You do have a point but I can't agree entirely. The number is correct for a
single drive, which is all I have in my PC.

The 300,000 drive array won't have many early failures unless it's been
constructed out of a random selection of new and second hand drives (maybe
that's what they meant by Redundant Array of Inexpensive Disks). Failure
rates typically follow what's known as the bathtub curve. Failure rates are
high at the beginning and end of the range of lifetimes. Quite a few drives
will die early (hopefully before they get out of the factory gates) but the
vast majority will keep going for a period close to the average.

The main point still holds good - hard disks are most likely to die of power
cycle related failures if aggressive power management is in use.


Best regards

Mike


> -----Original Message-----
> From: filmscanners_owner@halftone.co.uk
> [mailto:filmscanners_owner@halftone.co.uk]On Behalf Of Kapetanakis,
> Constantine
> Sent: 31 March 2003 15:54
> To: mike.brown@mindblown.com
> 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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