How to control fans in a power efficient way?

[Andrea3000]

Hi,

 

I’m putting together a low power, small form factor storage server running unraid.

 

It will have 8 HDDs with two fans cooling them.

 

The server will be idle for most of the day, with the hard drives spinned down. And during this time I’m aiming for the CPU to reach a low power state, at least C7.

 

I’m trying to find a way to control the two hard drive fans based on the HDD temperatures (with PWM).

The BIOS has a series of temperature sensors that can be used to control the fans, but the HDD temperature isn’t on that list.

 

I’ve seen few plug-in and scripts here on the forum to periodically read HDD temp and set fan speed accordingly, say every 5 seconds.

 

Do you know if running a script like that every 5 second “wakes” the CPU up from C7 (or higher) into a higher power state?

Are there hardware alternatives (fan controllers?) that can read the hdd temp and control the fans accordingly?

 

Thanks

Andrea