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Is there anyway to find out if a hard drive has spun down? I've been using the following command to spin it down after idle time:

hdparm -S 120 /dev/hdX

However im not sure it's working correctly and was wondering how to check the current power state to see if has correctly powered down.


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You can find out the power status with the -C flag to hdparm:

hdparm -C /dev/hdX

As explained by man 8 hdparm:


Check the current IDE power mode status, which will always be one of unknown (drive does not support this command), active/idle (normal operation), standby (low power mode, drive has spun down), or sleep‐ ing (lowest power mode, drive is completely shut down). The -S, -y, -Y, and -Z flags can be used to manipulate the IDE power modes.

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Caution: many people report that hdparm -C wakes up the drive and recommend using smartctl -i -n standby instead. (see… or – Benoit Blanchon Feb 26 '12 at 10:16
In testing BOTH hdparm -C and smartclt -i -n standby (Ubuntu Server 14.04.1 LTS) – STW Nov 10 '14 at 13:04

As I don't have hdparm nor smartctl available on my NAS I checked the /proc as I assumed that it had to be there somewhere, too.

Well, if it's down:

root@NAS:~# cat /proc/d_suspdtime
SuspendingTime = 15
Disk1: No_Disk

If the kitten would go crazy on it:

root@NAS:~# cat /proc/d_suspdtime
SuspendingTime = 15
Disk1: No_Disk

I also got

root@NAS:/proc# cat /proc/d_suspdtime
SuspendingTime = 15
Disk1: No_Disk

Guessing from some testing:

  • ACTIVE: the HDD did something within a certain timespan (it doesn't seem to mean that it does something right now)
  • NO_ACTIVE: there was some activity, but in a while it'll be going to standby
  • STANDBY: well, the HDD is in standby

And to be complete on this SuspendingTime is the time in minutes after the HDD should go to standby.

Since I'm no Unix-pro I can't tell if you are supposed to have /proc/d_suspdtime on your system, too (guessing from Google results it may be related to NAS or busybox).

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