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Blog / Windows 8 hangs due to 100% disk utilization


Windows 8 hangs due to 100% disk utilization


Some time after I installed Windows 8 on my machine, it stared interrupting my work by onsets of very slow operation. I noticed that the LED signaling disk activity was constantly on. Sometimes the interruptions were random, sometimes expected.

If I started an activity that demanded reading from disk, my system would go into a painful slowdown, and it would be almost impossible to continue normal operation until the disk operations are done. Windows was installed on a high-performance machine. System disk was an SSD, and I used an HDD for documents and files.

I hadn’t had these problems on Windows 7, so I thought this could be a Windows 8 issue.

I searched the Internet for a solution and came up with various fixes, hacks, partial solutions and explanations, but most of them didn’t work or made no sense; and there is always someone who suggests either scanning the system for viruses or reinstalling the whole system.

I’m writing this for those who might have come across this issue (and I reckon there are a lot people who did), so that you can perhaps fix it.

In my case, the HDD was tilting at 100%, not the SSD, but I’ve seen people saying their SSD is tilting.

If I started a virtual machine, I could be sure that the system was going to hang, simply because the virtual machine requires a lot of disk operations. After configuring each virtual machine to preallocate the memory the disk usage while the VM was on seemed to lessen, but was far from gone.

Usually when such activity starts, I open the Task Manager (Ctrl+Shift+Esc) to see which process is using the most disk resources. It seemed to be no process which was writing to disk or reading from it a lot. However, the disk activity was showing 100%. This means that the disk is constantly processing read/write requests.

I’ve managed to identify a few processes which could be slowing the system down. One of them was the Western Digital backup program. I disabled the startup of this program, but let its backup service run. The disk usage subsided slightly, but was definitely still too high.

Another program that was causing a lot of disk activity was the uTorrent client. I found a fix/improvement for this issue. Setting the caching in the uTorrent, reduced the number of disk operations (there is an “override disk cache” option, which I set to 256MB.

Besides that, I found people saying that installing/uninstalling Hyper-V could solve the problem of high disk usage. Also, running checkdisk could identify and fix disk issues (however, this process can take some time on large disks).

From the Resource Monitor (available either in Task Manager, or from Start Screen or Control Panel), I tried to identify those processes which used the disk most. In the disk tab of the Resource Monitor, I sorted the processes by total number of disk operations. Interestingly, the first in the list was System, svchost or avp.exe (which is the Kaspersky Internet Security process).

This explains a lot. The anti-virus monitors all processes, meaning it can slow them down by scanning the files they access or open. As for the system and svchost, this could suggest a bug in a system or some device driver.

I found that malfunctioned network driver could be causing this, so I updated my network drivers.

Next, I excluded my virtual machines directory from the anti-virus scanning, and added the virtual machine host application to the exclusion list of the anti-virus program (in my case Kaspersky Internet Security 2013). Also, I added the WD Backup Engine to the exclusions list (this should only be done if you know which folders the Backup Engine is scanning, so that it is safe not to monitor it).

Now, what was left was to try to fix the system issues. I went to BIOS to see my disk options and I noticed that I had left my SATA controller at its default option IDE. The IDE controller is supposedly slower than the AHCI controller. However, simply changing this option in the BIOS would make Windows 8 crash at startup because it wouldn’t have the proper drivers installed.

To change from IDE to AHCI, you can restart the system in the Safe Mode so that it can install the drivers it needs after changing the setting in BIOS. Basically, the process is as follows:

  • Tell the system to boot in Safe mode by holding the Shift key and clicking the Restart button and then going through the options screen (or check the link: Restarting Windows 8 in Safe mode): Troubleshoot > Advanced Options > Startup Settings > Restart
  • Before the system starts to boot (during the BIOS startup screen), enter the BIOS settings (by pressing Delete) and set the SATA controller to AHCI
  • When the system boots, it will display startup options and the safe mode option should be selected
  • The system should boot into safe mode with proper drivers installed
  • Restart the system normally and it should work with the new SATA drivers

There is also a registry hack that could achieve the similar effect, but it didn’t quite work for me. The above method worked fine.

The startup took around half a minute, which was significantly slower than the startup time on the IDE mode. Also, the system was incredibly slow. Moving the windows around was stuttering, everything seemed to be very slow, and the disk LED was constantly on. I checked the Resource Monitor, and the disk was tilting again. Interestingly, it was prefetch and indexing that were accessing disk the most (the avp.exe also had a lot of disk operations). However, now both the SSD and the HDD were tilting at 100%.

I installed the AMD SATA drivers, just to make sure that I have the newest drivers installed. (On a side note, I’ve read that at some point the Windows 8 default SATA drivers were better than AMD’s and that the Intel’s drivers were far better than both.) I restarted the system. The next startup was slow, but not as slow as the last time.

I decided to let it be slow for some time, and, if the performance issues persist, to later revert back to the IDE controller.

I continued working, and I’ve noticed that every time I open a program for the first time (since the change from IDE to AHCI), the system would hang for a moment. I checked the Resource Monitor, and found the most activity in Kaspersky and indexing. Perhaps Kaspersky had to rescan all the files because the controller was changed (this is a guess, I’m not sure why this happened).

After some time (hours), the system was operating normally. I checked the boot time and it seems to be slightly faster than earlier (before the IDE to AHCI change). The new configuration seems to work, and I haven’t had the disk tilting issues after the change.

People complain that the solutions they are offered are not working, but it might be that they are working partially. There are a lot of factors to be considered for this issue. However, to identify the causes you can try the following:

  • Use the Task Manager to identify the processes with high disk utilization and disable their startup if they are not necessary
  • Find Services that start up automatically and are not necessary and set their startup options to manual (this will make them start only when they are needed)
  • Use the Resource Monitor to identify the processes with most disk utilization
  • If you have any trusted programs add them to the anti-virus exclusions list
  • Add any virtual machine programs and directories to the anti-virus exclusions list
  • If you use backup programs, configure your backup plans correctly (you don’t need to scan all the directories for changes, only those that contain important files)
  • Configure your anti-virus to work best on your system
  • Configure each problematic program for better disk usage (for example, set the disk caching options for the uTorrent client)
  • Update your device drivers and disable devices that you do not use
  • Change from IDE to AHCI controller
  • Keep your disks clean – run disk cleanup, defragment and checkdisk (Windows 8 will do the defragmenting for you automatically)

EDIT: I have found a solution that worked for me: Windows 100% disk utilization solution. I replaced my WD Green drive with a new WD Black drive and the problem seems to be gone.

I hope this article will help someone who has the high disk usage issue. For any questions you can mail me at igor@igorsevo.com.

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