How do I get hard disks to spin down?
Solution 1:
You can use a linux command hdparm -S
man hdparm
-S : Set the standby (spindown) timeout for the drive. This value is used by the drive to determine how long to wait (with no disk activity) before turning off the spindle motor to save power...
Also look at this question:
What’s the effect of standby (spindown) mode on modern hard drives?
$ sudo hdparm -S 240 /dev/sda1
/dev/sda1:
setting standby to 240 (20 minutes)
Solution 2:
In Ubuntu it is sufficient to enter:
hdparm -S 240 /dev/yourdisk # spinoff after 20 minutes