Change Virtio SCSI to Virtio SCSI Single with Windows Server Guest

[dbayer]

Hello,

I've created a Windows Server 2019 guest with multiple drives. When doing a disk intensive operation it is causing a lot of IO Delay. When I created the Guest I did not set the SCSI Controller to Single.

Is it possible to change it to SCSI Single and IO Thread for each drive without causing issues to the Guest?

Thanks!

 

[wolfgang]

Hi,

It is the same driver, so yes, it should work.
With Win10, it works without problems.

But where do you have the IO Delay?
If it is on the host, the change of the io bus will not help.

 

[dbayer]

Hi,

It is the same driver, so yes, it should work.
With Win10, it works without problems.

But where do you have the IO Delay?
If it is on the host, the change of the io bus will not help.

Thanks for the quick answer.

It is on the host. The guest is essentially a new version of an old 2008R2 server. The IO Delay happens during a disk backup inside the Guest. The New Guest with Server 2019 takes an additional hour to finish the process compared to the old 2008R2 guest. I was hoping the SCSI Controller and IO Thread would help.

 

[wolfgang]

Backup with Proxmox VE internal Backup or is the backup done in the VM?

 

[dbayer]

It's Windows Server Backup running inside the VM to another Virtual Hard Drive attached to the same guest.

 

[wolfgang]

Maybe the Backup changed?
And they use now smaller blocks?

 

[dbayer]

I made a mistake. The Backup schedule starts an hour later, that's why it ends an hour later.

Just in case anyone else looks at this thread. I did change the Controller to VirtIO SCSI Single and change each hard drive to IO Threading. When you reboot windows you have to make all Drives other then the C Drive go back online. Other then that it worked fine. However it did not speed up the backup.