Kurvítka nonplusultra

[Pavel Troller]

Zdravím,

> On Fri, Feb 14, 2014 at 09:20:22AM +0100, Václav Ovsík wrote:
> > On Fri, Feb 14, 2014 at 06:39:20AM +0100, Pavel Troller wrote:
> > > Zdravim,
> > >   vypada to dobre.
> > >   Ma celkem najeto, ale vsechna data jsou vysoko nad prahem. Jednou v historii
> > > mu ale bylo hezky teploucko, 60 stupnu C, pokud interpretuji data spravne...
> > > Ta raw hodnota pri zvysovani teploty linearne klesa, cili kdyz pri 44 je 106,
> > > odpovida to odecitani od 150 a tedy v nejhorsim pripade 150 - 90 = 60.
> > 
> > To se mi nejak nezda, ten prepocet. Napriklad v jednom serveru mam
> 
> Tak jsem jeste chvili koukal do manu od smartctl a pisou tam:
> 
>   Each vendor uses their own  algorithm  to  convert  this "Raw" value
>   to a "Normalized" value in the range from 1 to 254. Please keep in
>   mind that smartctl only reports the different  Attribute  types,
>   values, and  thresholds  as  read from the device.  It does not carry
>   out the conversion between "Raw" and "Normalized" values: this is done
>   by the disk´s firmware.
> 
>   The conversion from Raw value to a quantity with physical units is not
>   specified by  the SMART standard. In most cases, the values printed by
>   smartctl are sensible.  For example the temperature Attribute
>   generally has its raw value equal to the temperature  in  Celsius.
>   However  in some cases vendors use unusual conventions.  For example
>   the Hitachi disk on my laptop reports its power-on hours in minutes,
>   not hours. Some IBM disks track three temperatures rather than one, in
>   their raw values.  And so on.
> 
> Tedy asi nejde predjimat jak to disk spocetl, pokud to fakt pro konretni
> disk nevite...

Ano, presne takto jsem se chystal odpovedet, ale predesel jste mne.
Shodou okolnosti mam pomerne hodne zkusenosti s ruznymi typy disky a zpusob
prevodu raw teploty na skutecnou odectenim od nejake horni meze, kterou lze
snadno zjistit, jak jsem puvodne uvedl, byva zejmena u starsich disku
relativne bezne. Zajimave je, ze jako prahova hodnota je uvedena 0, coz by
znamenalo indikaci selhani az pri 150C. To muze znamenat, ze vyrobce si
u tohoto disku nepreje, aby byla chyba prekroceni teploty reportovana.

Treba u meho disku jsou ty teplotni hodnoty 2:

190 Airflow_Temperature_Cel -O---K   056   041   045    Past 44 (0 105 47 41 0)
194 Temperature_Celsius     -O---K   044   059   000    -    44 (0 14 0 0 0)

A pak ta analyza vypada takto:
Current Temperature:                    44 Celsius
Power Cycle Min/Max Temperature:     41/47 Celsius
Lifetime    Min/Max Temperature:     14/59 Celsius
Under/Over Temperature Limit Count:   0/99153
SCT Temperature History Version:     2
Temperature Sampling Period:         1 minute
Temperature Logging Interval:        1 minute
Min/Max recommended Temperature:      0/ 0 Celsius
Min/Max Temperature Limit:            0/ 0 Celsius
Temperature History Size (Index):    128 (89)

Cili se zda, ze hodnota "Temperature Celsius" to meri od posledniho spusteni,
zatimco ta "Airflow" je naakumulovana behem cele doby zivota disku.
Jak ale z tech hodnot urci minimum/maximum, v tomto pripade uz neni zcela
zrejme. 

Zdravi Pavel