Enable hard drive standby / Advanced Power Management on Linux

My disks don't spin down, here's how I fixed it:

To check status without waking the drive:

sudo smartctl -i -n standby /dev/sda

To check status may wake drive:

sudo hdparm -I /dev/sda

To help hard drive goto sleep:

sudo smartctl --offlineauto=off /dev/sda

Disables SMART scrubbing (automatic offline testing), which helps the drive is to enter "standby". Note: offlineauto=off value is saved in the drive, surviving reboots and power outages.

To enable Advanced Power Management :

sudo hdparm -K 1 /dev/sda

-K     Set the drive´s "keep_features_over_reset" flag.  Setting this enables the drive to retain the settings for -APSWXZ over a soft reset (as done during the error recovery sequence).  Not all drives support this feature.

To check Advanced Power Management level:

sudo hdparm -B /dev/sda

To set Advanced Power Management level:

sudo hdparm -B 1 /dev/sda

-B     Get/set Advanced Power Management feature, if the drive supports it. A low value means aggressive power management and a high value means better performance.  Possible settings range from values 1 through 127 (which permit spin-down), and values 128 through 254 (which do not permit spin-down).  The highest degree of power management is attained with a setting of 1, and the highest I/O performance with a setting of 254.  A value of 255 tells hdparm to disable Advanced Power Management altogether on the drive (not all drives support disabling it, but most do).

To set spin down time:
sudo hdparm -S 120 /dev/sda
where 120 = 10mins
-S     Put the drive into idle (low-power) mode, and also set the
              standby (spindown) timeout for the drive.  This timeout
              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.  Under such circumstances, the drive
              may take as long as 30 seconds to respond to a subsequent
              disk access, though most drives are much quicker.  The
              encoding of the timeout value is somewhat peculiar.  A
              value of zero means "timeouts are disabled": the device
              will not automatically enter standby mode.  Values from 1
              to 240 specify multiples of 5 seconds, yielding timeouts
              from 5 seconds to 20 minutes.  Values from 241 to 251
              specify from 1 to 11 units of 30 minutes, yielding
              timeouts from 30 minutes to 5.5 hours.  A value of 252
              signifies a timeout of 21 minutes. A value of 253 sets a
              vendor-defined timeout period between 8 and 12 hours, and
              the value 254 is reserved.  255 is interpreted as 21
              minutes plus 15 seconds.  Note that some older drives may
              have very different interpretations of these values.

Apparently sdparm can be helpful if hdparm does not work. I've not tested this yet...
To install:
sudo apt install sdparm