I want to extend a running KVM Linux guest system with a physical hard drive. I’ve connected the new disk via
virsh attach-disk my_vm /dev/sdf vdc
to connect sdf to vdc, but inside the guest, nothing happens.
The solution is simple: attaching a new disk requires a new virtio block controller which is a PCI device. The trick is to rescan the PCI bus system to detect the new controller:
echo 1 > /sys/bus/pci/rescan
Now lspci shows the new controller and dmesg shows the new vdc block device.
00:08.0 SCSI storage controller: Red Hat, Inc Virtio block device
Simply load the both modules
then you don’t need to rescan the PCI bus.