PowerNap waking my external TB Hard Drive


macrumors newbie
Original poster
Sep 27, 2011
Yesterday I setup and configured my rMBP as a desktop replacement in my bedroom office. It had the lid closed, but it was connected to a Thunderbolt Display, which in turn had a USB Keyboard, Mouse and Lacie TB 2Big Drive attached.

All night long, once every hour (I know because it woke me up and I checked the clock, very annoying, sleep deprived...) my Lacie would wake up, the drives would spin up and the very bright blue LED would turn on, waking me up. After 8 seconds or so it would shut down and go back to sleep. I wish I could go back to sleep that easily... Anyway, as I had installed the PowerNap upgrade a week ago, I thought this might be a symptom of that feature. However, I thought the concept of PowerNap was to only use flash and avoid anything that would alert the user that it was awake (like turning on fans, mechanical HDs, etc). Am I mistaken, will external hard dives always wake during a PNap state, or does this sound like it is not working as intended? For tonight I have disabled PNap entirely, but I'd love to find a way to suppress the external drive awakening.

One other thought I had was about a little Lacie utility, "Raid Monitor" that runs in the top right menu bar. It just reports if there is a drive issue. Perhaps that process gets run during a nap wake cycle and it stats the drive causing a wake, and then the whole machine sleeps again 8 seconds later? I suppose I could try disabling that utility too.

Or perhaps this issue has nothing to do with PNap? Has anyone else experienced anything like this?

Thanks for any info!


macrumors 65816
Jan 5, 2003
Dallas, USA
It's not PowerNap spinning up the HDD. It's the HDD spinning up the HDD. PowerNap powers the ports and most HDDs that spin down when port power cuts spin up when port power is restored. My external HDD, which is my active Time Machine volume but that's not relevant to cause here, connected via USB spins up whenever PowerNap does its thing. And then spins down again after a brief interval when PowerNap goes back to sleep. But my rMBP is on my desk downstairs and I don't hear it in the middle of the night. I guess move the rMBP or disable PowerNap or eject and disconnect the external volume before you hit the rack.