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Possible Duplicates:
hard drive activity by program?
What is causing hard drive grinding?

Once or twice a day my computer starts writing significantly hard to the hard drive, the HD led is ON and the performance hit is noticeable. A strange observation is that the Task Viewer does not show I/O activity - even Process Explorer shows no CPU activity and no I/O bytes read or written.

Is there a way to know which application is using the hard drive and how much data is it reading or writing?

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marked as duplicate by Revolter, random Aug 19 '11 at 12:20

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

This has been asked before. You can find more info here: or here:… – alex Jan 20 '10 at 8:46
The answers there does not apply to my question as I said that the Process Explorer is not showing anything. – Ignacio Soler Garcia Jan 20 '10 at 9:32
@Ivo - this is not a duplicate, as he tried the solutions on the other questions, and they are not working for him, as he explained. This is a different problem. Commenting over the other question won't help him, as he can't describe his problem, he would only be able to post an answer... And this is not an answer, it's a question. Voting to reopen. – Gnoupi Jan 20 '10 at 9:38
Voila :) Though I hope someone will actually solve his problem here then! – Ivo Flipse Jan 20 '10 at 10:06

Windows 7 and 8 has a nice and improved Resource Monitor that shows some nice stats about the current disk activity.

Resource monitor screen shot

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Windows Xp here :\ – Ignacio Soler Garcia Jan 20 '10 at 9:14
Thanks! For me 'Resource Monitor' shows the I/O as belonging to "System" - I wonder if procexp isn't accounting for it because of that (though procexp does account for CPU use by 'System"). Anyway, 'Resource Monitor' also shows the file(s) that are accounting for the I/O , so it's clear that Firefox is responsible. Time to restart my browser. – Michael Burr Nov 21 '13 at 5:33

I find it really strange that Process Explorer is not showing it. It should show all processes, normally, and you should see the culprit in it.

Try eventually with Process Monitor. It will be more messy and will require filtering, but at least you should find for sure what is using your hard-drive.

procmon screenshot

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As far as I know ProcessExplorer does not show system HD activity. Maybe I can try with Process Monitor but will be hard to diagnotic anyway due to the fact that when this happens the performance degradation is really heavy. – Ignacio Soler Garcia Jan 20 '10 at 9:33

I agree that Process Monitor is far too bulky and burdensome both in usage and resources.

Since you are running Windows XP, you can still use FileMon. However, you’ll have to find a copy since Mark pulled it once he released ProcMon (even though RegMon/FileMon are much faster and easier to use).

For an even lower-level view, you can use DiskMon, though it does not show process information.

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