Hello List,
By default CONFIG_USB_SUSPEND is not enabled and today I got bite by
this when I got a new WDC My Book hard drive. I have no way to unplug
it safely, according to it's manual, with a kernel that doesn't have
CONFIG_USB_SUSPEND=y.
On it's manual read "you should unplug and remove the device only when
the light is off." On Linux unmounting it won't turn it's light off
and I can feel it's motor is still running. The only way to unplug it
properly on a Linux system, as to my knowledge, is to echo `suspend'
to `/sys/bus/usb/devices/$DEV/power/level'. And one has to have
CONFIG_USB_SUSPEND=y to do this.
On Windows and Mac OS, `safely remove this device' function effectly
turns it into `suspend' mode, and it's light off.