Re: Rebooting and HDD spinup / spindown cycles [WAS: Re: Debian Wheezy - HP Pavilion dm1]
On Wed, 2013-10-23 at 12:44 +0000, Curt wrote:
> On 2013-10-23, Ralf Mardorf <ralf.mardorf@alice-dsl.net> wrote:
> >
> > Isn't that plausible? I'm the source, I care for facts, not for claims
> > from vendors.
>
> >From your favorite company:
>
> <research.google.com/archive/disk_failures.pdf>
>
> Power Cycles. The power cycles indicator counts the
> number of times a drive is powered up and down. In
> a server-class deployment, in which drives are powered
> continuously, we do not expect to reach high enough
> power cycle counts to see any effects on failure rates.
> Our results find that for drives aged up to two years, this
> is true, there is no significant correlation between fail-
> ures and high power cycles count. But for drives 3 years
> and older, higher power cycle counts can increase the
> absolute failure rate by over 2%. We believe this is due
> more to our population mix than to aging effects. More-
> over, this correlation could be the effect (not the cause)
> of troubled machines that require many repair iterations
> and thus many power cycles to be fixed.
>
> Power-on hours. Although we do not dispute that
> power-on hours might have an effect on drive lifetime,
> it happens that in our deployment the age of the drive is
> an excellent approximation for that parameter, given that
> our drives remain powered on for most of their life time.
>
> Key findings:
>
> · Contrary to previously reported results, we found
> very little correlation between failure rates and ei-
> ther elevated temperature or activity levels.
> · Some SMART parameters (scan errors, realloca-
> tion counts, offline reallocation counts, and proba-
> tional counts) have a large impact on failure proba-
> bility.
> · Given the lack of occurrence of predictive SMART
> signals on a large fraction of failed drives, it is un-
> likely that an accurate predictive failure model can
> be built based on these signals alone.
Don't confuse
12 Power_Cycle_Count
with
193 Load_Cycle_Count
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