Dear all, although I fear I am already foreseeing the answer, I'd like to ask if it is possible to pass through a single SATA port at hardware level to a Windows guest. I already have successfully passed through whole SATA controllers (i.e. with all their ports) as well as single drives as block devices, but this is not sufficient for the scenario below: I have a dual XEON server with a mainboard which has only one SATA controller with 6 ports. This server runs debian stretch and hosts various virtual machines, one of them being a Windows 2008R2 server (I'll call the latter just "the guest" in the following sections). The guest is started from a disk image, but for certain reasons additionally needs direct access to one single big backup disk. Since the mainboard has only one SATA controller, the backup disk is connected to the same SATA controller as the rest of the disks where the host Linux system resides. The backup disk is hot-swappable. Currently, I have configured the system so that the backup disk is recognized by the host Linux system as block device (in my case /dev/sda) and is passed through to the guest as block device. I am starting the guest via command line directly (no libvirt or virsh or something like that involved) using the following option: -drive file=/dev/sda,format=raw,if=virtio,cache=none,index=1 This setup works reliably, but is a nightmare when the backup disk must be changed. Currently, to change that disk, I am - shutting down the guest (because I have found no way to let the guest (or qemu-kmv?) treat that drive as a removable drive; - removing the drive from the Linux host (by doing something like sync; echo 1 > /sys/block/sda/device/delete); - inserting the next backup disk; - restarting the guest VM. Actually, this is not acceptable, notably the need to shut down the guest to remove the backup disk. So my goal is to let the guest treat the backup disk like a removable drive. Of course, I can't pass through the SATA controller to the guest because then I couldn't connect the disks which contain the host system anywhere. Passing the disk as a block device to the guest does not help either because it does not seem to be possible to pass it as a removable drive. So I was hoping that I could just pass through one of the SATA ports to that Windows guest, and that this would make it possible (perhaps by some registry hack) to make that disk removable from within Windows. Is this possible, or does anybody have another idea how to solve that problem? My last resort currently would be to put a PCIe SATA adapter in the server, connect the backup disk there and pass through the new adapter's controller chip to the guest. Regards and thanks for any help, Binarus
