I have just bought a My Cloud Mirror with the exact same problem. I would like to share some of my findings.
From the dashboard, there is a process list with one called fan_control. It seems to be related to the fan problem.
I enabled the SSH and then login. Type the command will show a list of available options. There are many for temperature and fan control.
~ # fan_control -?
*** Fan Cobtrol Help Message ***
fan_control b c: for NAS booting
fan_control 0 d : [auto: low/medium/high/max] open debug msg
fan_control 0 c : [auto: low/medium/high/max] close debug msg
fan_control -L [value] : set Lower (THYST)
fan_control -H [value] : set Upper(TOS)
fan_control -g 0 : get current temperature
fan_control -g 1 : get Lower temperature
fan_control -g 2 : get Upper temperature
fan_control -g 3 : get fan state
fan_control -g 4 : get fan rpm
fan_control -f 0 : set fan stop
fan_control -f 1 : set fan rpm4000
fan_control -f 2 : set fan rpm5000
fan_control -f 3 : set fan rpm6000
fan_control -f 4 : set fan rpm7000
fan_control -f 5 : set fan rpm8000
fan_control -f 6 : set fan rpm9000
The command “fan_control -f 3” can manually turn it on. Its noise and air flow can be easily detected. The larger the number, the faster is the fan speed. The command “fan_control -f 0” can manually turn it off. The fan is working !!!
The commands “fan_control -g 0” would give the hard drive temperature. “fan_control -g 4” give the fan RPM. The figures are the same as in the dashboard.
Using these commands, I have managed to bring down the temperature from 55 back to 45 manually.
So the problem is not in the fan but in the automatic temperature control. Perhaps some DIY people can write a background monitor program to check the temperature and change the fan speed periodically.
Another finding is a file called /etc/fan_temperature.txt Its contents is here:
~ # cat /etc/fan_temperature.txt
TEMPERATURE_STOP = “39”
TEMPERATURE_LOW = “45”
TEMPERATURE_HIGH = “49”
However, I have not tested whether this text file is for documentation only or it has any real threshold function.
Hope these findings would be helpful to you all.