External hard drive spinning up during sleep Every time I close the lid on my macbook air, my external hard drive seems to spin up for about 5 seconds every 30 seconds, and this will go on continuously, even for several hours. The noise itself isn't too loud, so I don't really have a problem with that, but I'm worried it might damage the hard drive.

Is this normal OS X behaviour (I'm on Mountain Lion, sleep mode 3), or is it specific to my model of hard drive (Samsung 1tb USB 3)? I read that Mountain Lion will supposedly check emails and perform updates during sleep, could that be the cause?

If it doesn't harm the hard drive, I'm not too worried, but if repeated spinning up will exert extra strain, I'd like to find a way to stop this happening.
Unfortunately, Mac OS doesn't eject hard drives when the machine enters sleep. And since your MacBook performs some "activity" during sleep, a writing/reading process might keep the hard disks awake.

There are at least three solutions to this problem:

A) You eject the hard disks each time before you enter sleep

B) You get the Jettison App for $4.95 (http://www.stclairsoft.com/Jettison/), which automatically ejects hard disks before the MacBook enters sleep, and mounts them when the MacBook awakes. There is a 15 days free trial if you like to check if it works for you.


C) Disable the Power Nap mode