Searching a little on the forum, this question has been asked before and never got a authoritative answer by D-Link staff.
The best founded hint, coming from old FW release notes, is that trigger temperatures could be 43, 46 and 49 celsius. This is typically interpreted as fan stopped below 43, over this starts at low speed (less than 3000rpm), at 46 goes to medium speed (somewhere at or above 4000rpm), and full speed is fired up at 49 (6300rpm or so).
Note that, by most accounts, units rarely go over 44-45 degrees whatever the load, so in fact fans are likely to be working typically at low speed. Have observed that low speed is so silent that you can easily think it's stopped, and the air flow is also barely noticeable with your fingers only (had to introduce a small point of paper and hear it hitting the fan to be sure it was on). But they don't go below this, either, and most people feels this as too warm for the disks.
The message for D-Link FW programmers is that most people feels not comfortable with this operating temperatures, we would like to keep our beloved disks at lower temperatures, so a most aggressive setup would be very welcome by users.
Or even better, allow us to make adjustments without recurring to FW hacks. Today, our only 'official' option is to set fan to permanent full speed, and that seems just an overkill on the opposite side, producing unnecessarily noise and wear when the unit is idle. The truth must be in the middle, something like being able to set a reasonable target temperature, around which fan speed increases to whatever is needed to keep it there, or simply to full speed until is somewhere below the target.
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Topic: fan thermostat (Read 6561 times)