Manually putting external USB drives into standby

Manually put a USB HDD that doesn’t automatically spin-down after inactivity to sleep by:

  1. Install sg_start

    apt install sg3-utils
  2. Determine which /dev/sd* with:

    df -h
  3. assuming the HDD to spin down was at /dev/sdc:

    sg_start 0 --pc=3 /dev/sdc
  4. The HDD wakes up automatically when writing/reading a file on it.

Why spin down hard drives?

  • HDDs put out substantial heat when spinning
  • However, don’t spin up/down too frequently (< 5 minutes) to avoid excessive wear.