A SCSI controller of type VirtIO SCSI single and enabling theIO Thread setting for the attached disks isrecommended if you aim for performance. This is the default for newly createdLinux VMs since Proxmox VE 7.3. Each disk will have its own VirtIO SCSI controller,and QEMU will handle the disks IO in a dedicated thread. Linux distributionshave support for this controller since 2012, and FreeBSD since 2014. For WindowsOSes, you need to provide an extra ISO containing the drivers during theinstallation.