cutting power to usb flash drives

hobylinux · 08-28-2003, 12:19 AM

quick question. my flash drive works fine (well, one of them), but i just have one question. when i unmount the drive, the light is still on, which i'm guessing means that the power is still going to it. is it safe to remove like this? is there any way to power it down in linux?

thanks.

faheyd · 08-28-2003, 02:47 AM

Does that light stay on in XP? If so, it might just be a status light meaning it's plugged in. Please go to the hardware vendor site and see if they can give you info on the function of that light and when is it a. on b. off c. blinking , etc.
Or post the vender and make/model and hope someone here has the same thing and can tell you.

hobylinux · 08-28-2003, 08:16 AM

its a sandisk cruzer. and no, the light does not stay on in xp. in xp, after clicking the button to safely remove hardware, the light goes off.

tozgrec · 08-31-2003, 12:35 PM

There are 3 kernel-modules wich deals with this:
1) usb-core
2) usb-uhci or usb-ohci (depends on your hardware)
3) usb-storage

so, after unmounting USB device, you should use the following commands (as root)

#modprobe -r usb-storage
#modprobe -r usb-uhci
#modprobe -r usb-core

...and the USB's light will go off. (it works well for my own Xonix usb-storage).

In order to find if your PC uses usb-uhci / usb-ohci, you can ust the following comand, AFTER the mounting of usb device:

# lsmod

(this will show you you all running kernel modules)

hobylinux · 08-31-2003, 10:22 PM

hmmmm.....

that doesn't seem to work for me. i put in my sandisk cruzer, mounted it, and used lsmod. it showed usb-storage and usbcore running. i then unmounted the device and ran:

#modprobe -r (module)

for all the usb modules. however, the light didn't go off. then, i tried to remount the device in order to try it again. upon doing that, i was told that /dev/sda1 did not exist. however, i had just mounted the device a few seconds before. any thoughts?

gregtrounson · 08-09-2007, 09:14 PM

Quote:

Originally Posted by tozgrec

There are 3 kernel-modules wich deals with this:
1) usb-core
2) usb-uhci or usb-ohci (depends on your hardware)
3) usb-storage

so, after unmounting USB device, you should use the following commands (as root)

#modprobe -r usb-storage
#modprobe -r usb-uhci
#modprobe -r usb-core

...and the USB's light will go off. (it works well for my own Xonix usb-storage).

In order to find if your PC uses usb-uhci / usb-ohci, you can ust the following comand, AFTER the mounting of usb device:

# lsmod

(this will show you you all running kernel modules)

That's not going to work if you have other USB devices plugged in. I think what he wants is what Windows users see. When a drive is unmounted, power to that port alone is cut and the drives light goes out. A rather sensible safeguard to teach your users if you ask me: "If the little light is on, don't pull it out".