Hard drive spin down

[croth56]

I have a Macbook pro early 2011. I have two internal hard drives (optibay). I have searched the forums regarding spinning down a drive that I am not using.
My question is how do I know when my hard drive has spun down in the optibay ? How do you tell when a hard drive is not spinning ?

Thanks

 

[dusk007]

You should be able to tell the noise. If the fans spin at 2000 rpm and the second drive is an ssd a spun down hdd makes a big noise difference. One has to be deaf to not hear it.

If you have two hdds and cannot hear the difference (between one and two) in noise, I don't really see the point of spinning it down. An HDD even just spinning idly needs like 0.8W. Personally I think noise is the only reason why one would want the drive to spin down.

You can tell if you install the Developer tools and launch the App "SpindownHD" via Spotlight.

It says sleep if it is spun down. Mine currently is not.

 

[croth56]

I am not concerned so much about noise (30 years in manufacturing has taken care of that). I was more concerned at trying to save some battery life. They are two hard drives (no SSD). The one in the optibay more for storage.Don't really access it a lot. Thanks for the reply

 

[Intell]

You can set up a launch daemon that runs a script every 7 seconds to check if the drive is mounted and if it isn't, run a eject command to make it spin down.

 

[dusk007]

If it idles for X to 10 min it will spin down on its own. Unmounting is only useful if one is like a data graveyard you don't need that often and there are some annoying apps running that keep it from actually idling.
Spotlight with NTFS Partitions effectively never lets a drive idle. There are some bugs and some monitoring software is also wonko.

You won't save much battery life. The average consumption on really low load that you get 7h run time with is 10W. 10.6W barely changes a thing. Even spun down a drive still ciphers off about .15W. If the load is more medium and or you run the display at higher settings it is practically nothing.
I wouldn't go through the hassle of unmounting and the low response time when needed for anything other than noise.

 

[croth56]

Thanks for the input. Guess I'll just leave it as is. I was just curious how everyone new when their hard drive had spun down

 

[Intell]

Mine spins down almost instantly after unmounting it or after something like Spotlight spins it up again.

 

[dusk007]

An unmounted drive should always immediately spin down and never spin up unless there is some diskutil command involved.
But if you do not unmount it and only rely on the idle time for it to spin down on its own then I have experienced lots of bugs. All sorts of stuff can keep it from spinning down even if it is really just a data drive with stuff on it that no application should ever need.
Running my data drive in exFAT works but using NTFS on just one partition on there breaks it unless I unmount NTFS.

 

[Intell]

Internal unmounted drives rarely spin down when unmounted and they usually spin back up again after because of Spotlight or the system polling the drive. Externally unmounted drives do normally spin down when unmounted, because they are ejected. You can't eject an internal drive unless you use a terminal command. And even then the system can spin it back up because it detects it as a non-removable drive.