Manually put a USB HDD that doesn’t automatically spin-down after inactivity to sleep by:
apt install sg3-utils
assuming the HDD to spin down was at
sg_start 0 --pc=3 /dev/sdc
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.