Fan behaviour

af123

Administrator
Staff member
My new (to me) Foxsat is running a bit warm for my liking so I've been observing the fan behaviour to see what it does when left alone before I do something to fix it. Didn't find it documented anywhere so, for the record:

The Foxsat firmware triggers the fan based on the temperature of the hard disk drive, specifically attribute 194; the fan speed is controlled via pulse-width-modulation (PWM)*.
The system starts with the fan turned off and leaves it off until the temperature reaches 51 centigrade at which point it sets it to half speed (0x7fff) until it drops again to 46° at which point it turns off.

Looking at the code**, there are two other fan speeds used making the full set:

< 47°C - off
> 51°C - 0x7fff (50%)
> 62°C - 0xa491 (64%)
> 64°C - 0xc923 (78%)

* The PWM has 16-bit resolution (compared to 8-bit on the Freeview T2).
** I'm not getting my disk hot enough to verify by observation!
 
OP
af123

af123

Administrator
Staff member
Yes, I'd imagine so.

If I set my fan to run at 40% minimum then the temperature just about holds steady so the 50% that it engages is just enough to start cooling the disk down.
 

Mike0001

Well-Known Member
This is what Seagate have to say about HDD temperature.

What is the normal operating temperature for Seagate disk drives?
The drive should never exceed the temperature ranges below. If the drives ever exceed these temperature ranges then the drive is considered "overheated" or is not getting adequate air flow from your current case environment.

With our newer model drives the maximum temperature is now at 60 degrees Celsius.

The operating temperature range for most Seagate hard drives is 5 to 50 degrees Celsius. A normal PC case should provide adequate cooling.

However, if your enclosure is unable to maintain this range, we suggest that you contact your system manufacturer for information on cooling and ventilation hardware that is compatible with your specific configuration.

The answer to this question depends on your case environment. If you have adequate cooling, it is probably not necessary. If you feel that you need additional cooling, use your favorite internet search engine and enter the keywords "drive bay cooling kit".
 

Mike0001

Well-Known Member
WD give 65C as the maximum running temperature, though running at over 60 is going to considerably reduce the lifespan.
 

Black Hole

May contain traces of nut
Why? 60° isn't particularly warm for the semiconductors. Maybe thermal expansion of the bearings would cause extra wear, but that depends how they are designed and I expect that to have been taken into account.

The upper (and lower) temperature limits of the drive specification are a reflection of how they are tested off the production line, and guaranteed to operate correctly over those extremes, with no guarantee of correct operation outside those limits (but no certainty of incorrect operation either). It doesn't imply failure (as opposed to misoperation) or reduced lifetime, you need to look for specific manufacturer information about that.

Temperature may have an effect on the platter's recording medium.

Old stepper motor drives would have had more trouble with thermal effects than current voice-coil designs. With stepper motors to position the read/write head, the head had to position itself over the track by dead reckoning, so any shift by thermal expansion of the platter would try to read a track from off-centre or write a track in the wrong place. Voice-coil designs, apart from being able to cope with much finer track spacing, are servo controlled and able to track position shifts due to thermal effects.
 
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Black Hole

May contain traces of nut
I'd still rather run the fan constantly at a lower speed than have it kick in hard at a threshold, although at least the Foxsat doesn't do what the T2 does and bring it on at maximum.
Absolutely, although I think a proportional system with much finer fan drive resolution would be better still.

Operating temperature (drive case temperature) 0° to 75°C
This supports my point. I doubt AV drive mechanics are designed any differently, it's simply that set top box manufacturers, with a huge buying power, were able to demand that drives are tested (and therefore guaranteed operational) over a wider temperature range so that they can be run fanless.

I was just trying to find out how Mike justifies his assertion that failure rate increases over 60°.
 

Ezra Pound

Well-Known Member
. . . at least the Foxsat doesn't do what the T2 does and bring it on at maximum.

The Foxsat way is a much better idea, I would think that 95% of the time it never gets above 50%, it hard to believe these products are made by the same company as they are inconsistent, I'm not sure which product came first, but they obviously didn't see the need to make both products do the same thing
 
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af123

af123

Administrator
Staff member
I was just trying to find out how Mike justifies his assertion that failure rate increases over 60°.
https://www.backblaze.com/blog/hard-drive-temperature-does-it-matter/

After looking at data on over 34,000 drives, I found that overall there is no correlation between temperature and failure rate.

HOWEVER, none of their drives get anywhere near hot.
Google have also published a report in the past saying they can't find a correlation and they do run their drives hotter. The Google article is linked to from the Backblaze one.
 
OP
af123

af123

Administrator
Staff member
I'm not sure which product came first, but they obviously didn't see the need to make both products do the same thing
I think it was the Foxsat. My best guess is that with the T2 they wanted to run fanless for as long as possible to minimise noise - I just think they made the wrong choices.

Absolutely, although I think a proportional system with much finer fan drive resolution would be better still.
... and I could implement that, but is it really worth me putting the time in?

I do have a fan package for the Foxsat in testing though that does the same as the T2 one.
 

Mike0001

Well-Known Member
Google have also published a report in the past saying they can't find a correlation and they do run their drives hotter.
Actually, the Google one showed a massively increased chance of failure when run hot at an age of about 2 to 3 years. And hot meant less than 50C, too. They seem not to run any drives at 60C, for obvious reasons.

https://static.googleusercontent.co...ch.google.com/en/us/archive/disk_failures.pdf

Sorry, BH, I was totally wrong again. I would start to worry at 40C after reading this report.
 
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