[SOLVED] Verify VirtIO driver working? - poor performance after enabling Bitlocker (only one vm, other is fine)

[Jason2312312]

After enabling BitLocker on a Windows Server 2019 VM, I noticed a significant decline in performance. Interestingly, I performed the exact same BitLocker encryption on a another 2K19 VM and observed no noticeable impact on its performance.

To troubleshoot, I updated the VirtIO driver, but the drivers are the same on both VMs and thus could not be updated. The performance degradation is similair to running the VM without the VirtIO driver.

This performance issue is evident even when the system is idling or by simply opening the Event Viewer, tasks that have no impact on the other VM's performance. Left is the VM with issues, on the right the VM which is running fine:




I will try to disable Bitlocker and see if the issue persists, in the worst case I have a backup I can restore,
but I would like to figure out what caused this issue as I see no evidence of the VirtIO driver malfunctioning.

Any insights in how to troubleshoot this further is greatly appreciated, I will update when I have disabled Bitlocker.

 

[Jason2312312]

With Bitlocker disabled I get similar results:

 

[alexskysilk]

After enabling BitLocker on a Windows Server 2019 VM, I noticed a significant decline in performance.

It does that on storage that doesnt have Windows supported SED. Since virtio doesnt support sed passthrough (not afaik) its probably that you just have a different virtio configuration on your vms which explain the perceived difference in performance between your two vms.

It PROBABLY would work with a direct disk passthrough, assuming your disk is SED capable and supported by Windows, but at that point its probably better to just install windows on the metal.

 

[_gabriel]

Windows disable its writecache when AD role is enabled.

 

[Jason2312312]

And.... I found the reason, I put the OS disk the NFS storage rather than the SSD. I feel stupid but this is how we learn right
After moving it runs smoothly now