On Tue, Nov 20, 2018 at 03:15:54PM +0200, Peter Dimitrov wrote: > This problem occurs on certain machines but I can't tell why and how > exactly to fix it. > > The message suggests a problem with kernel modules, but they all seem to > load successfully, including many virtio modules. These are quite old versions of kernel/qemu/libguestfs/supermin so I can only really offer general advice. You are right that the problem is caused because the appliance kernel does not see any virtio-scsi disks. That can be for a variety of reasons such as: - The virtio drivers in the appliance are not loaded or not working for some reason. - qemu isn't presenting virtio devices to the guest. From the trace: libguestfs: libvirt XML:\n [...] <devices> <controller type="scsi" index="0" model="virtio-scsi"/> <disk device="disk" type="file"> <source file="/tmp/libguestfsdTUUkY/overlay1"> <seclabel model="selinux" relabel="no"/> </source> <target dev="sda" bus="scsi"/> <driver name="qemu" type="qcow2" cache="unsafe"/> <address type="drive" controller="0" bus="0" target="0" unit="0"/> </disk> <disk type="file" device="disk"> <source file="/tmp/libguestfsdTUUkY/overlay2"/> <target dev="sdb" bus="scsi"/> <driver name="qemu" type="qcow2" cache="unsafe"/> <address type="drive" controller="0" bus="0" target="1" unit="0"/> <shareable/> </disk> This ought to cause libvirt to tell qemu to present virtio-scsi devices. You can check if they are actually present on the qemu command line by looking for /var/log/libvirt/qemu/guestfs-XXX.log supermin: internal insmod crc32c-intel.ko supermin: internal insmod virtio.ko supermin: internal insmod virtio_ring.ko supermin: internal insmod virtio_blk.ko supermin: internal insmod virtio_console.ko supermin: internal insmod virtio_net.ko supermin: internal insmod virtio_scsi.ko The Virtio SCSI driver is getting loaded. supermin: internal insmod virtio_balloon.ko supermin: internal insmod virtio_input.ko supermin: internal insmod virtio_mmio.ko supermin: internal insmod virtio_pci.ko [ 0.289514] virtio-pci 0000:00:02.0: PCI->APIC IRQ transform: INT A -> IRQ 10 [ 0.289888] virtio-pci 0000:00:02.0: virtio_pci: leaving for legacy driver [ 0.290355] virtio-pci 0000:00:03.0: PCI->APIC IRQ transform: INT A -> IRQ 11 [ 0.290768] virtio-pci 0000:00:03.0: virtio_pci: leaving for legacy driver [ 0.291008] virtio-pci 0000:00:04.0: PCI->APIC IRQ transform: INT A -> IRQ 11 [ 0.291392] virtio-pci 0000:00:04.0: virtio_pci: leaving for legacy driver This indicates that the Virtio PCI transport module is being loaded. The "virtio_pci: leaving for legacy driver" message is worrying. I think what's happening here is your appliance kernel only has drivers for virtio 1.0 ("virtio modern") but your qemu is presenting virtio legacy drivers. There's a kernel config option to enable virtio legacy (VIRTIO_PCI_LEGACY) which you should probably try first. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top