Admin Stuff

Linux does support dynamic power management of usb discs. The only difficult part is to find the place in /sys. Here a shell function to do that:

 # 'powerpath /path/to/dev/node' gets the path of the /power directory
 # for that device
 powerpath() {
   devpath=$(udevinfo --query=path --name="`realpath $1`")
   case "$devpath" in
   /block/*/*) devpath=${devpath%/*} ;;
   /block/*) ;;
   *) return 1 ;;
   esac
   echo $(realpath /sys$devpath/device/../../../../power)
 }


To suspend a disk with label backup:

 echo 'suspend' >`powerpath /dev/disk/by-label/backup`/level

And to bring it back up

 echo 'on' >`powerpath /dev/disk/by-label/backup`/level