# Why does external HD (judging by its lights) never stops puttering, even after 10 hrs of CPU sleep? **URL:** \ **Category:** Factual Questions\ **Created:** [April 25, 2016, 3:32pm UTC](https://boards.straightdope.com/t/why-does-external-hd-judging-by-its-lights-never-stops-puttering-even-after-10-hrs-of-cpu-sleep/753097 "2016-04-25T15:32:08Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [April 25, 2016, 3:32pm UTC](https://boards.straightdope.com/t/why-does-external-hd-judging-by-its-lights-never-stops-puttering-even-after-10-hrs-of-cpu-sleep/753097/1 "2016-04-25T15:32:08Z")
See query. Macbook. I understand that while the computer is in operation, or shortly after a shutdown, housekeeping is required, or even if the auto-save Time Machine needs to wake itself up, check for somnambulation, and maybe has to tell the HD to stand down, wheels are spinning. But I come in this morning after what I thought was a long quiet night for all three of us, it’s percolating away. Howcum? ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [April 25, 2016, 3:40pm UTC](https://boards.straightdope.com/t/why-does-external-hd-judging-by-its-lights-never-stops-puttering-even-after-10-hrs-of-cpu-sleep/753097/2 "2016-04-25T15:40:55Z")
> [@Leo\_Bloom](#): > > See query. Macbook. I understand that while the computer is in operation, or shortly after a shutdown, housekeeping is required, or even if the auto-save Time Machine needs to wake itself up, check for somnambulation, and maybe has to tell the HD to stand down, wheels are spinning. > > But I come in this morning after what I thought was a long quiet night for all three of us, it’s percolating away. Howcum? are you sure the drive is actually doing something? even during sleep PCs and Macs usually maintain USB power so the system can wake if you press a key or move the mouse. The light may be on simply because the external drive enclosure is still receiving power over USB, while it’s long since told the drive to turn off/spin down. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [April 25, 2016, 6:29pm UTC](https://boards.straightdope.com/t/why-does-external-hd-judging-by-its-lights-never-stops-puttering-even-after-10-hrs-of-cpu-sleep/753097/3 "2016-04-25T18:29:37Z")
Oh, that’s why I mentioned the “flickering/puttering”…most definitely doing something. If it weren’t in digital, in the old days I would’ve heard the gears shifting/crunching. BTW, that drive has two partitions: the Backup, and one other for miscellaneous media stuff. When I dismount one (do they still say that?) one, out goes the other–but the Backup partition, judging by the Finder status, has become much more stodgy over the last month, i.e., slow to come on-line after the Media portion is up, and slow to leave (by its file list, at least). Any chance that’s related, in the sense of systemic trouble? which worries me about the drive a lot more than its chattering to itself. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [April 25, 2016, 7:04pm UTC](https://boards.straightdope.com/t/why-does-external-hd-judging-by-its-lights-never-stops-puttering-even-after-10-hrs-of-cpu-sleep/753097/4 "2016-04-25T19:04:05Z")
First of all, what makes you think your Mac is asleep? ---
**Author:** ![Doug\_K](https://avatars.discourse-cdn.com/v4/letter/d/b5ac83/32.png) [@Doug\_K](https://boards.straightdope.com/u/Doug_K)\ **Post date:** [April 25, 2016, 9:43pm UTC](https://boards.straightdope.com/t/why-does-external-hd-judging-by-its-lights-never-stops-puttering-even-after-10-hrs-of-cpu-sleep/753097/5 "2016-04-25T21:43:48Z")
> [@Leo\_Bloom](#): > > Oh, that’s why I mentioned the “flickering/puttering”…most definitely doing something. If it weren’t in digital, in the old days I would’ve heard the gears shifting/crunching. > > BTW, that drive has two partitions: the Backup, and one other for miscellaneous media stuff. When I dismount one (do they still say that?) one, out goes the other–but the Backup partition, judging by the Finder status, has become much more stodgy over the last month, i.e., slow to come on-line after the Media portion is up, and slow to leave (by its file list, at least). > > Any chance that’s related, in the sense of systemic trouble? which worries me about the drive a lot more than its chattering to itself. What do you mean by “in digital”? All mass storage drives are digital. Is it HD or SSD? If it’s an HD, you’ll be able to feel it spin no matter how quiet it may be. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [April 26, 2016, 1:35am UTC](https://boards.straightdope.com/t/why-does-external-hd-judging-by-its-lights-never-stops-puttering-even-after-10-hrs-of-cpu-sleep/753097/6 "2016-04-26T01:35:18Z")
> [@beowulff](#): > > First of all, what makes you think your Mac is asleep? I would ask this too. Modern machines that are connected to the net tend to chatter with the outside world quite a lot, even you think the machine is idle. A few years ago, I was playing with Wireshark a lot, which shows you all the net traffic coming into and out of your machine. There seemed to be a fairly steady stream of messages coming in and out all the time. ---
**Author:** ![jasg](https://avatars.discourse-cdn.com/v4/letter/j/f0a364/32.png) [@jasg](https://boards.straightdope.com/u/jasg)\ **Post date:** [April 26, 2016, 2:12am UTC](https://boards.straightdope.com/t/why-does-external-hd-judging-by-its-lights-never-stops-puttering-even-after-10-hrs-of-cpu-sleep/753097/7 "2016-04-26T02:12:11Z")
Q1 - is your Mac really asleep? On my old MacBook & Mini there is a white LED ‘heartbeat’ that dims and brightens when asleep. Q2 - have you looked at Acivity Monitor (Utilities folder) to look at disk activity? Lots of info on the web on how to use & interpret.