How to automatically turn off hard drive when not used? [duplicate]

hardware hard-drive gnome-disk-utility

I have a noisy hard drive I rarely use and want to silent. I would like to put it in sleep mode after some time (20 sec) when it's not mounted on the system.

The gnome-disks utility shows a "standby timeout" option: enter image description here enter image description here

The hard drive never gets to sleep automatically; I can manually put it to sleep/wake it up with the gear menu: enter image description here

Why does my drive doesn't automatically go to sleep? How can I make it go to sleep automatically after no activity?


This part from Put HDDs in standby after X minutes using hdparm doesn't work might help:

Is AHCI enabled in your BIOS? If not try turning it on and re-trying.

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