S.M.A.R.T. Temperature is very high even when the drive is cool to the touch

[Enys]

The temperature I am getting from two new hard drives do not make sense.  Immediately after starting a server that has been off all night, I get '176' as my drive temperature, then it climbs to the low 180s.  Even if it is in fahrenheit, that's over 77 degrees celsius.  Output for one of the drives is below.  Am I reading something incorrectly? 

esxcli storage core device smart get -d t10.ATA_____TOSHIBA_DT01ACA300_________________________________16SUPMJKS

Parameter                     Value  Threshold  Worst

----------------------------  -----  ---------  -----

Health Status                 OK     N/A        N/A

Media Wearout Indicator       N/A    N/A        N/A

Write Error Count             N/A    N/A        N/A

Read Error Count              100    16         100

Power-on Hours                100    0          100

Power Cycle Count             100    0          100

Reallocated Sector Count      100    5          100

Raw Read Error Rate           100    16         100

Drive Temperature             176    0          176

Driver Rated Max Temperature  N/A    N/A        N/A

Write Sectors TOT Count       200    0          200

Read Sectors TOT Count        N/A    N/A        N/A

Initial Bad Block Count       N/A    N/A        N/A

The drives are cool to the touch even when the Drive Temperatures is in the 180s.  I'm not too worried, but I'd sure like to understand it.

Thanks!

[JarryG]

First of all you have to understand that SMART attributes are highly vendor-specific. Each drive manufacturer defines his own set of attributes and threshold values. Moreover, those attributes are seldom pure physical values, mostly they are calculated using some formula.

Drive Temperature             176    0          176

I'm pretty sure this is not directly drive temperature, because threshold value (the worst one, you should never reach) is zero. In other words, in this case the higher value the better. If this value starts dropping, approaching "0", then you'd have reason to worry. Not now.

Similar for all other values, i.e. "reallocated sector count 100" does not mean your drive already reallocated 100 sectors, it is just information you have still plenty of spare sectors (in this case 100%) that can be used for reallocating. Or "power cycle count 100" does not mean you powered on/off your drive 100 times, it means from the number of expected power-cycles your drive did not use much, and still has about 100%. Etc, etc. You can get more accurate representation of smart-values from your drive-vendor (some send you detailed specification if you ask for it). But there is definitely nothing wrong in your smart-output. The other point is a hard-drive might fail even if its smart-values were all perfect just a minute ago...

[Enys]

Thanks, JarryG!  I appreciate your clear and detailed explanation.