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Slow Windows guest with 100% disk usage

PostPosted: 14. Aug 2019, 01:26
by llamafilm
For a long time I have suffered very slow performance in Windows 10 guests. Task Manager shows 100% disk usage although the speed is not very high. In this screenshot it's showing 45MBps read speed. The host is a MacBook Pro with flash storage over 1500MBps. I'm using a fixed size VDI. I'm currently on VirtualBox 5.2.22 but this has been happening for a long time across multiple versions. Is this a known issue and is there any way to make it access the disk image faster?

Re: Slow Windows guest with 100% disk usage

PostPosted: 14. Aug 2019, 02:02
by socratis
Moving to "Windows Guests" from "OSX Hosts".

llamafilm wrote:this has been happening for a long time across multiple versions. Is this a known issue and is there any way to make it access the disk image faster?
Yes. Talk to Microsoft and see what the heck they're doing. I swear I'm going to get a screenshot of my physical Win10 installation and have it handy when a question like that comes up! :)

Having said that, there is one thing to check in your VM Settings » Storage » select your SATA controller » Use Host I/O Cache, check that.

Re: Slow Windows guest with 100% disk usage

PostPosted: 14. Aug 2019, 02:24
by llamafilm
Hi socratis. I'm not sure what you mean by this. I do not have this problem on real Windows machines. The slowness seems to be particularly bad anytime Windows Update or "antimalware service executable" is running, but I think this is simply because they do a lot of disk I/O.
I already have Host I/O cache enabled for the SATA AHCI controller.

Re: Slow Windows guest with 100% disk usage

PostPosted: 14. Aug 2019, 18:11
by socratis
llamafilm wrote: I do not have this problem on real Windows machines
I do. Exactly that problem.

llamafilm wrote:The slowness seems to be particularly bad anytime Windows Update or "antimalware service executable" is running
At this exact time. If you take a look at the Processes in the Task Manager, that's exactly what you see. And I'm still talking about my real PC.