Checking if hard disk is powered off?

[heycam]

Hi everyone.

I have my Mac Mini set to power off hard disks after some time of inactivity. I think my external USB hard disk is not being powered off. Is there some way I can check this? Is there an equivalent of the hdparm utility in Linux?

Thanks,

Cameron

[DeltaMac]

The setting is to put the drive to sleep, if possible - not cutting the power to the drive.

Querying the drive would usually power it on, I think, if it is sleeping.

Why would you want to know if the drive is actually off? You can always eject the drive, and turn off the power.

Shutting the mini off will probably power down the external drive completely, if the drive supports that action.

[heycam]

The setting is to put the drive to sleep, if possible - not cutting the power to the drive.

Oh, ok. I assumed it would power it down completely.

Querying the drive would usually power it on, I think, if it is sleeping.

Maybe. But using hdparm in Linux I can query to see if the drive is in one of three states: "active/idle (normal operation), standby (low power mode, drive has spun down), or sleeping (lowest power mode, drive is completely shut down)". I assume that means that it needs only to query the IDE controller and not the drive itself.

Why would you want to know if the drive is actually off? You can always eject the drive, and turn off the power.

I want to know if the power settings are having the effect I want. What I'm doing is using an external hard drive as a backup for my laptop, but the backup will only run every X days. During the rest of the time, I want the hard disk off so that it doesn't waste power. (Related to my other question.) And I want this to happen without me having to unplug and replug the USB cable myself.

Shutting the mini off will probably power down the external drive completely, if the drive supports that action.

It probably would. But I want the mini running the rest of the time, even when the backups aren't happening.

Thanks,

Cameron

[DeltaMac]

And I want this to happen without me having to unplug and replug the USB cable myself.

I don't think you would need to actually unplug the drive. If it's only used every few days, just dismount the drive, and turn the drive power off. It should mount if you turn the drive power back on. That would prevent the system from occasionally querying the drive, and mounting again when you don't intend for that to happen. That could happen if you rely on some software command to turn the drive power off. This would probably happen if you wake up the mini from sleep.