udisks --detach ... How do I do the reverse?
 

My latest toy is a Dell Inspiron Micro - about the size of a CD wallet. I am running it headless with Ubuntu Mate 15.04 as a jobs/download server and basically a test/toy. The measured power consumption is less than 4 watts at idle. Quite amazing I think. I have added a Seagate 1TB usb drive to the machine. This bumps up the power consumption to just under 6 watts. A 50% increase :cry: So, as this is for testing and experimenting I tried unmounting the drive and powering it down with udisks --detach. This does not seem to work - the light stays on on the drive and the power consumption does not change. I will work on that later or try a Toshiba drive which seems to be better at actually powering down. The drive has in fact disappeared as I can no longer mount it. But I digress...

As this machine is run headless and "remote" (it is tucked away under the desk and not convenient to get physical access to) I am wondering how I can power on the drive without unplugging and plugging the USB cable or rebooting the machine.

I have looked at the man page for udisks and I have not found any option which seems to do the trick. I see reference to "device_file", however, I do not know what this file refers to. Is is something created by the system? something I need to create? Is it totally irrelevant to my need? Any and all advice appreciated.

TIA,

Ken

Changes have been made at the kernel level with regards to USB power management

https://www.kernel.org/doc/Documenta...management.txt

I haven't had the need to turn a device off completely, and from what I've read the attached devices are supposed to implement power management, with the kernel driver just responsible for the signalling to do so. Anyway, I can really only help by pointing you at some discussions on this topic with various approaches employed (and why things may or may not work as expected)...

http://askubuntu.com/questions/34206...-off-usb-ports
http://unix.stackexchange.com/questi...-usb-subsystem
http://stackoverflow.com/questions/4...off-with-linux

Thanks ferrari,

I will give those links a read.

Ken