I set Windows 7 to turn off hard disks after 20 minutes of nonuse, which it does a really good job at - it seems to turn off individual hard disks that have been idle for 20 minutes exactly. When I access a drive that I haven't used in 20 minutes, I can hear it firing up and it takes a couple of seconds to access it.

Now Windows is turning off and turning on my hard disks several times a day.

Can this on/offing be bad for the drives? The case is small and I'm trying to protect the drives from overheating really (they get VERY hot!).

Edit: The accepted answer doesn't mention this explicitly, but from Minimizing hard disk drive failure

Power cycling control

Shutting down and rebooting a computer or resuming it from hibernation cycles the power to the drives in the computer. The spin-up operation performed by a drive after a power cycle is believed to place more stress on the drive than running the drive continuously for a long period of time.

Based on professional experience of system administrators, it is believed that there is a direct relationship between the number of power cycles of a computer and the probability of failure of its drives**. In other words, a computer with a high uptime may have a lower probability of drive failure than one that has its power cycled routinely.

** Attribute #4 of S.M.A.R.T. is Start/Stop Count, which seems to indicate that start/stop count DOES play a role in disk fitness and when to expect a failure.

See also

... Energy Star compliance results in an increase in daily power up/down cycles. The consequent thermal shock and mechanical stresses on the system can adversely affect its life...

  • I now use HD Tune to monitor my disk health
    – bobobobo
    Jan 22, 2011 at 12:30
  • 3
    I see a lot of believes in that quote. There’s just too much conjecture and speculation which only fuels the fires of doubt. :-(
    – Synetech
    Jun 28, 2012 at 3:16
  • @Synetech - Speculation shouldn't dissolve into doubt by default. It seems plausible even without empirical data.
    – Enigma
    Mar 21, 2013 at 20:35
  • 1
    "plausible even without empirical" is a non-argument!
    – JasonXA
    Dec 4, 2015 at 9:12

7 Answers 7


Google showed that heat has very little effect on hard drive life expectancy, despite anecdotal claims to the contrary. See this paper. The paper was by far the largest study on the subject. Note, though, that Google keeps their drives running 24/7, so there was no information on specifically whether turning off your hard drives was harmful, only that you don't need to worry so much about temperature.

  • 7
    ^not any more...
    – Sponge Bob
    Aug 21, 2012 at 21:23
  • 6
    An overview of the publication can now be found here: research.google.com/pubs/pub32774.html and the paper here: research.google.com/archive/disk_failures.pdf
    – alexteg
    Oct 22, 2012 at 19:56
  • 5
    Reference for next time that the link dies: Pinheiro, Eduardo, Wolf-Dietrich Weber, and Luiz André Barroso. "Failure Trends in a Large Disk Drive Population." FAST. Vol. 7. 2007. Dec 18, 2013 at 17:54
  • If you look at the charts, running the drives too hot does increase the failure rate. It's just that the threshold for problems is a lot higher than anyone expected (and just as unexpectedly, there's also a lower temperature threshold: running your disks too cold increases the failure rate).
    – Mark
    Jun 10, 2019 at 21:33

Spinning down hard disks does help in reducing overall heat and also increasing its life.

However, there are reports that a lot of HDD failures happen when restarting a disk after the spindown.

This ServerFault answer to
What’s the effect of standby (spindown) mode on modern hard drives?
talks about it

More opinions on this are welcome.
I am also investigating the stability of using an older laptop with an alternate USB boot.

  • 3
    > However, there are reports that a lot of HDD failures happen when restarting a disk after the spindown. I think as a general rule of thumb, it would be safe to say that turning a drive on and off through normal power-management (hours between startup/shutdown events) is fine. The real problem is when the drive is rapidly turned on and off as when the power connector to the drive is loose and the power keeps getting cut and restored.
    – Synetech
    Jun 28, 2012 at 3:19

My (totally anecdotal) experience has been that drives that spin down do reduce electrical consumption costs (and associated cooling), but fail marginally more often. I felt this was a bit of a loss overall for the environment, since I'm minutely saving electrical consumption at the cost of filling a landfill slightly faster.

It is hard to figure out precisely what is going on, since it is usually single-disk workstations which are the best candidate for stopping idle drives; however since they are single drives, the OS likes to go and touch things on it occasionally.

  • "t the cost of filling a landfill slightly faster", technically, this remark is inacturate. Powering up mostly puts pressure on the elctronical part of the drive. If you're in a country whre WEEE (waste) isn't proessed, then yes, but if dirives can be recovered by replacing a few resistors, then the landfill won't see them. And believe me, the bigger the drives are the more interest there is to recover them. 20GB 15y old drives... I would see the issue in putting the work to repair them, 2y old 2TB drives... heck, why not!
    – JasonXA
    Dec 4, 2015 at 9:18

If your drives are getting so hot, it is probably due to ventilation issues not disk issues. If you are taking proper steps to make sure computer is properly ventilated (and I assume your computer is not all that old if it's running windows 7) there might be something wrong with your computer. All I need to do is keep mine propped up an inch or two and it never gets that warm. If I have to leave it on overnight or for a long time, I turn it onto it's side. If it is resting flat on a surface, that is what is heating your computer up as I frequently leave my 5 year old laptop running overnight simply on it's side and it has never been an issue.

If you're the kind of person who lets their computer idle for a few hours and then starts back up again on and off through out the day, I would not recommend allowing it to continually stop and start your drives. This is hard on your computer and I have in fact damaged drives in the past doing this constantly, though this was on an older computer, I hear the newer ones have similar issues and I'd rather not be so hard on the drives since they contain valuable work.


A lot of "best-practices" for drive management are based on conjecture--actual objective data to back up particular claims is few and far between.

For your case the question is "which is worse, the heat or the spin-up?" personally I'd lean towards spinning the drives down if you can--they won't be as hot and they won't heat the rest of the machine up as much.

  • 2
    Further, a lot of anecdotal evidence is based on the way drives were designed 10, 20, 30 or even 40 years ago, and is totally irrelevant to modern drive design. May 20, 2013 at 21:14

Turning on things make them peak in power consumption and it is unstable (the powerconsumptuin, for the time it starts up). Both this stress the the electronics (esp electromechanical things) a lot.

In the case of harddisks, constant heat ins't good either (especially desktop grade harddisks).

But as Yoooder mentioned what is the worse in exactly your case is hard to say.

Personally I rather have the disk on all time (unless on laptop with just battery), but afaik I don't got any heat problem (ofc harddisks get warm but thats normal).

  • Yes, I see a reference for this at en.wikibooks.org/wiki/…. "The spin-up operation performed by a drive after a power cycle is believed to place more stress on the drive than running the drive continuously for a long period of time." Also, using passmark.com/products/diskcheckup.htm, there IS a field for Start/Stop Count.
    – bobobobo
    Aug 7, 2009 at 3:10

The "spin down" or "power saving" mode for HDD's can be bad for certain SSD's, apparently: http://www.tomshardware.com/forum/272075-32-sleep

  • 1
    How? If anything SSDs would be more suited to frequent on/off because they have no moving parts Jul 19, 2012 at 13:41
  • I'm referring to the old "spin the hard drive down" sleep mode. tomshardware.com/forum/272075-32-sleep Seems a reference.
    – rogerdpack
    Jul 19, 2012 at 15:59
  • 2
    Please expand your answer, if possible, to something longer than a sentence. If you could add the link and a little context, that would be great.
    – slhck
    Jul 19, 2012 at 23:54
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    Yes, well power cycling is what will do it. This article says a PCB has 90k power cycles before it kaputz. SSD's are already low power as they are. There is no need to expose them to power cycling this way.
    – bobobobo
    Jul 21, 2012 at 1:10
  • 2
    When a computer spins down a HD while the computer in general remains up, power is not removed from the HD's PCB! The drive is just sent a command to power-down the drive motor. (If this were not the case then spinning the drive back up by sending it another command could not work.) So "spin down the drive to save power while the OS runs" does not power-cycle the drive's PCB. Now, most drive failures happen on the PCB (believe it or not - hence the market in replacement PCBs for failed drives). So I don't think you can apply a principle about power-cycling PCBs to this question. Sep 11, 2016 at 22:27

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