Cooling tips?

[Ric Hardacre]

So my NAS is sat in a clear space, under a desk in a cool, dark corner of the room. The disks report a temperature of approx 32 degrees C . The internal temp often sits around 40 to 44 degrees. I've fiddled with the fan settings but basically the only way to keep the temp down is for the fan to be on for about a quarter of the time, which is quite annoying. I've taken the plastic lid off the box, thinking that might help convection cooling. 

So yeah, anyone got any tips on keeping it cooler , bigger quiet fan perhaps? Strip all the plastic from the outside to increase air convection more? bury it 10 feet underground?

[Norbert Horváth]

I did a few searches on the internet a bit earlier (DNS-320), here is what I found: the fan itself is not very bad, and it's running on 5V, so there aren't many better and affordable ones to replace. Fan control can not help, only you can choose between hot and loud. People successfully tried to make it more silent by disassembling the NAS and cutting the grating behind the fan, it seems that the noise comes from the moving air, not the fan itself. If I take the top off, it isn't cooler, but only louder.
My hope is that Joao will some day make a kernel with wireless support, so I can stick a wifi dongle into the usb and put it in the coldest part of the house for the summer... :)

[Paulo Elifaz Andrielli]

I was trying to create a second fan (from an old power supply), and put in front of the NAS, extracting the power from the USB. But no time to make this.... :-(

But as Norbert said, the noise is from the space between the walls in the back of the unit. Adding a foam between them will solve the issue

[]'s
Paulo
sent from Android

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[Norbert Horváth]

My plan was similar, to put a second fan on top of the disks and blowing downwards. It might fit, but USB is also 5V and 12V fans (old CPU fans in my drawer) usually don't even start at 5V.
My DNS-320 has an 5V fan, but I think other models use 12V fans that can be more easily replaced or duplicated, but the Y-cable might confuse the speed detector.
There were people who put RAM sinks on the CPU and the other chips to spread the heat, they found no effect on system temperature...

[João Cardoso]

On Saturday, 23 July 2016 10:17:38 UTC+1, Norbert Horváth wrote:

My plan was similar, to put a second fan on top of the disks and blowing downwards. It might fit, but USB is also 5V and 12V fans (old CPU fans in my drawer) usually don't even start at 5V.
My DNS-320 has an 5V fan, but I think other models use 12V fans that can be more easily replaced or duplicated, but the Y-cable might confuse the speed detector.
There were people who put RAM sinks on the CPU and the other chips to spread the heat, they found no effect on system temperature...

I made my own experiments on a dns-320L, and concluded that it's bad thermal design. That's why an "always off/low/fast" option exists for the fan speed controller -- as I didn't found a reasonable solution, that's your decision.

Removing the top cover only worsens things, as the fan aspirates air from the top (the lower air resistance path), not cooling the lower box section where the electronics (and "system" temperature sensor) are located.

The DNS-327L, similar to the 320L in design, has a larger and quieter fan, and the box bottom cover is completely "perforated" as well as the lateral inner metallic frame, improving convective cooling. But even so the fan turn on/off cycle on the dns-327L exists and is annoying, if compared with the dns-323/325 which I also own.

Another possible static solution for the 320L would be to imitate the 327L and perforate the box lower sides and the metallic inside frame, improving static convection from the side bottom and exhausting from the fan opening (even with the fan off). That could be effective when the disks are in standby, and could reduce the on/off fan cycle when they are working. But its out of my manual abilities to do it and keep the box nice looking.

And you had to do some math, to determine the effective area of air intake from these lateral (bottom) perforations and related it with the fan opening area to maximize static convection.

Notice that I'm not a cooling engineer, I'm a physicist by education ;-)

[Ric Hardacre]

I might have time to experiment this weekend, I've had it switched off for a couple of weeks now. I wouldn't mind so much if the fan only came on when the disks were in use but to have it constantly switching on and off while the box is nominally doing nothing is just plain weird!

[João Cardoso]

On Wednesday, 5 October 2016 10:49:55 UTC+1, Ric Hardacre wrote:

I might have time to experiment this weekend, I've had it switched off for a couple of weeks now. I wouldn't mind so much if the fan only came on when the disks were in use but to have it constantly switching on and off while the box is nominally doing nothing is just plain weird!

I found that without disks and the top lid closed, a 320L system temp is stable and constant at around 35ºC.

As soon as I plug in a 10 years old energy-inefficient disk and put it in standby mode, the box system temperature rises at about 1ºC per minute, and

so the fan turns on/off on a 10/15 minutes cycle to keep the system temperature within the bounds set in Services->System->sysctrl, Configure.

For most modern drives its quiescent power consumption is lower, and the system box temperature rise is slower, but nevertheless the temperature will rise and the fan will have to be turned on to exhaust the heat; you can only increase the turn on/off cycle.

I suggest that you put the fan always-off, the disks in standby, and watch the disk temperature rise; when the disk temperature attains its upper safe limit, take a note on the system temperature and then put the fan in automatic mode within that system temperature.

You can also try the following script as an alternative to 'sysctrl', but keep one eye in the system temperature, that is not monitored.

#!/bin/sh

# UNTESTED

# This script stops the system fan controller and turns the fan on or off accordings to the sda disk power state.
# If you have two disks you have to adapt it.
# The desired fan "speed" is written to /tmp/sys/pwm1 and
# read by an always running 'dns320l-daemon' or 'dns320-temp.sh' process (DNS-320/320L/327L)

rcsysctrl stop # this daemon does more than just fan control, it also controls buttons and leds. Turn it on after playing with this script

while true; do

if $(hdparm -C /dev/sda 2>&1 | grep -q active); then # disk is active

echo 127 > /tmp/sys/pwm1 # fan slow

#echo 255 > /tmp/sys/pwm1 # fan fast

else # disk standby

echo 0 > /tmp/sys/pwm1 # fan stop

fi

sleep 60 # wait 60 secs for next check, It could be 300, 5 minutes

done