Comment 76 for bug 435190

Interesting. Please try to boot into runlevel 3 (to avoid the desktop starting devkit-disks-daemon), ensure that devkit-disks-daemon isn't running and then put the drive asleep (or wait until it is asleep). Then as root run this command

 # /usr/libexec/devkit-disks-helper-ata-smart-collect /dev/sdb 1

replacing /dev/sdb with whatever disk it is. If the drive is asleep we should print

 Disk /dev/sdb is asleep and nowakeup option was passed

and exit with exit code 2. Otherwise it will dump a base64 encoded blob of the smart data to stdout and exit with exit code 0.

If this wakes up the disk it's probably a libatasmart bug - we've already identified a few issues with detecting whether a disk is asleep/awake in libatasmart (which is why I'm adding the libatasmart author to the Cc).