I noticed that my external hard drive, which uses a cheap SATA to USB enclosure, was constantly spinning, even when I hadn’t accessed it in hours.
I decided to lookup how to coax the drive to spin down.
A little searching showed that you can check a drive’s status and set its idle
timeout policy with the
$ sudo hdparm -C /dev/sdb /dev/sdb: drive state is: active/idle
Setting the timeout is a little odd, the value
120 means 10 minutes. See the
man page for details.
$ sudo hdparm -S 120 /dev/sdb /dev/sda: setting standby to 120 (10 minutes)
I also read that some drives don’t obey hdparm, so you may want to checkout
hd-idle if your drive won’t idle.