What can cause HDD activity when computer is left idle? My HDD is quite loud and I want to get rid of the noise when computer is idle.

It happens on Windows 7, automatic defragmentation and antivirus background scanning are turned off. Recently noticed it happen also while running Windows 10 TP install (which is installed on another drive - SSD, but the activity is still on HDD). I've looked into Resource manager - "Processes with Disk Activity" and found only system processes there, svchost.exe mainly - does it mean, it's some service causing this HDD activity? How do I found out which one?


Based on PID I've found out which svchost process is causing it. enter image description here

  • I don't know but resource monitor will also give you a PID so telling you which svchost.exe it is, but there are still a load of DLLS within svchost.exe even for one PID, as Process Explorer will show you. So how you'd find which one is using it I don't know. Process monitor might show you disk activity if you filter for `C:` but it will show you so much
    – barlop
    Commented Jun 3, 2015 at 20:37
  • capture a xperf traceof the activity: pastebin.com/AyxAVU60 Simply run it from a CMD, wait until your PC is idle and starts the HDD activity. Now wait 1 minute, go to the CMD again, press a ey to stop the tracing. Compress the ETL and share it. Commented Jun 4, 2015 at 3:42
  • Depending on your computer case (e.g. if it is a laptop then you are out of luck), you can mount the HDD so that it does not transmit so much noise to the outside world. A search for "quiten hdd" will give many methods. Commented Jun 16, 2016 at 20:01

5 Answers 5



I had the same problem in Windows 10: after about 5 minutes of system idle, there was a lot of disk activity on data disks (non swap, just data files), which disappeared on just a single mouse move.

The Task Manager didn't show much. The Resource Monitor did show that svhost was causing the disk activity, but didn't show which sub service of it was causing it.

Process Explorer ( https://technet.microsoft.com/en-us/sysinternals/processexplorer.aspx ) does show the sub services. After about 5 minutes of mouse/keyboard idle, defrag.exe started under svchost.


You can disable it (scheduled defragmentation, the cause) via the Task Scheduler > Task Scheduler Library > Microsoft > Windows > Defrag > then disable the "ScheduledDefrag". Disabling it removed the problem on my system.


Defrag is used to defragment the hard disk. For example, a file can be stored in multiple fragment spread over the hard disk. When the file is read, the hard disk head has to physically move to all the fragments sequentially, which requires some time and thus costs some performance. The defrag process moves the fragments to optimal locations, so that the hard disk head has to move less physical distance, which improves hard disk read and write performance.

Windows starts the defrag process automatically using the Task Scheduler when you idle for 5 minutes, but you can also manually start defrag: right click on a drive letter > Properties > Tools > Optimize. The fragmentation percentage indicates whether there is a need to defrag.

SSDs don't need to be defragmented, because there is no physical head movement. Using defrag on a SSD lowers the life expectancy of a SSD.

  • 1
    I've disabled numerous things in addition to defrag. Still the wakeups are coming. They are coming from explorer.exe, Windows Defender MsMpEng.exe (even though I added the drive to the list of Defender exclusions), and from svchost.exe (which could be any service, since they are idiotically in the same executable: good luck).
    – Kaz
    Commented Sep 24, 2020 at 21:19
  • @Kaz Windows Search indexing service may also cause such activity. You may want to try to disable it.
    – Devabc
    Commented Sep 24, 2020 at 22:36

The Windows Task Scheduler starts running various tasks including the ones you mentioned when the computer has been idle (no user interaction) for 4 minutes. You'd think there would be a way to alter that to a higher value. Search the web for schtasks.exe or Windows Task Scheduler for more information.


Svchost is a host process for many services. You'll need to use a tool like Sysinternals Process Explorer to look at the specific instance of svchost to see which service it's running (you can see it by hovering over the process).

My guess is that it's probably the indexing service scanning your data for faster searches. Could also be windows update writing temp files...

  • My bet was on the indexing service too, but it looks like it's not the case, check the screenshot in update.
    – mondzi
    Commented Jun 6, 2015 at 10:24

Have you tried checking under the advanced power options?

Win 7

  1. Open Control Panel
  2. Click power options
  3. Click Change plan settings on the plan you currently have selected, or create a new one.
  4. Click 'Change advanced power settings'
  5. In the list there should be an option to expand a section called 'Hard Disk'
  6. Once expanded there is a option to 'Turn off the hard disk after'
  7. By default for the Balanced power plan it should be set to 20 minutes, I would try increasing or decreasing to get your desired time.

I do not have a PC that I can test this on for Windows 10. However, I would image that you can find the options in the same/similar place.

  • I don't want the HDD to be turned off every 10 min...Still, I don't know if this would apply to this case, because HDD is active.
    – mondzi
    Commented Jun 6, 2015 at 10:32

In addition to what has been answered here, all of which were good answers, btw; another thing your HDD is doing quite often is getting the exact physical location of the cylinders. As the temperature of the hard drive changes the physical disks expand, and the temperature fluctuates depending on hard disk activity. Your hard disk controller needs to know where the cylinders are so that the arm can be exactly positioned at the cylinder where the requested sector is. This activity cannot be turned off.

  • 1
    Ok, but how often does this need to be done? The activity I described happens nearly every time PC is left idle.
    – mondzi
    Commented Jun 6, 2015 at 10:22
  • I didn't mean to imply that this was the only reason for the idle disk activity, just one of many.
    – BillDOe
    Commented Jun 7, 2015 at 1:59
  • 2
    Do you have a citation for this? I have never heard of anything of this kind, and I know a lot about how hard drives work. As far as I know, they seek based on the "servo tracks" on the hard drive platters on an as-needed basis. Commented Mar 12, 2016 at 21:42
  • 1
    @MichealJohnson, sorry, the information came from a white paper written by the then CEO of Seagate. I have not been able to find it since and don't have a copy of it (or if I do, I haven't been able to find it). In it, he said that hard drives over a certain size have one platter devoted just to cylinder IDs, rather than including cylinder ID information in the sector IDs. Probably no hard disks made today have cylinder ID information contained within the sector ID. It's more efficient to put cylinder IDs on one platter.
    – BillDOe
    Commented Mar 13, 2016 at 1:53
  • 1
    Having cylinder IDs on a separate platter (which I seem to remember hearing of before) is quite a separate matter to periodically "recalibrating" the seek mechanism due to temperature changes. While temperature changes probably will alter the seek distance required, there are many other things that also alter the seek distance required and that is the purpose of the "servo tracks" - whether those are interspersed with the sectors, in parallel with the data tracks (as I believe was the case at one time), or on a separate platter. Commented Mar 13, 2016 at 10:30

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