[smartmontools-support] WD WD101EFBX drive has insane temperatures?

[Franc Zabkar]

I'm wondering whether the "4" is a case where the normalised value has 
exceeded the limit of 256 and wrapped to 0. If so, then its actual value 
would be 260.

Assuming this is the case, then the weird normalised temperatures start 
to make sense if we interpret them as Fahrenheit rather than Celsius. 
The raw values would still be reported in Celsius, though.

I say this because I was involved in a forum thread (I can't find it 
now!) where a Hitachi drive reported similar weird values. 
WD101EFBX-68B0AN0 is probably a rebadged HGST model with HGST firmware 
architecture.

This was my reply in that other thread:

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I think that Hitachi's Temperature attribute (0xC2) is calculated so 
that a normalised value of 100 represents a baseline of 131 Fahrenheit. 
Thereafter each drop in temperature by 1 degree F increases the 
normalised value by 2. Higher numbers correspond to lower temperatures, 
meaning that this attribute reflects the "health" of the drive.

200 -> 27.2C = 81F​
181 -> 32.5C = 90.5F​
136 -> 45C = 113F​
100 -> 55C = 131F​
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-Franc Zabkar