Please keep me CC-ed as I'm not subscribed.
Some time ago a mail about turning of the leds on usb pendrives once unmounted by hal was send to the fedora-devel list:
This mail talked about echo 2 > power/state for usb devices.
I tested the method described in the mail to turn of the drive light and it worked well.
As I think that turning of the drive led (as windows does) would be good visual feedback to the end user that its safe to remove the device I've written a patch for hal which does the power state change automatically when the last partition of a usb massstorage device gets unmounted.
However when testing the patch I found out that my now newer kernel no longer has power/state for usb devices, it only has power/level. I can send suspend to power/level, but then remounting the device won't work and me syslog fills itself with:
sd 2:0:0:0: [sdc] READ CAPACITY failed
sd 2:0:0:0: [sdc] Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK,SUGGEST_OK
sd 2:0:0:0: [sdc] Sense not available.
sd 2:0:0:0: [sdc] Write Protect is off
sd 2:0:0:0: [sdc] Mode Sense: 00 00 00 00
sd 2:0:0:0: [sdc] Assuming drive cache: write through
Because hal keeps polling the device.