I converted qcow2 image to raw and changed I/O bus to VirtIO for a VM. now I can't boot that VM. I Installed VirtIO driver with following command:

mkinitrd --with virtio_pci --with virtio_blk -f /boot/initrd-$(uname -r).img $(uname -r)

and these are related kernel modules:

virtio_balloon         11329  0
virtio_blk             11593  3
virtio_pci             11845  0
virtio_ring             8513  1 virtio_pci
virtio                  9541  3 virtio_balloon,virtio_blk,virtio_pci

and this is what happens during boot-up.

I also changed /boot/grub/device.map from "(hd0) /dev/sda" to "(hd0) /dev/vda"

but problem still exists. any ideas how to fix this ?

This is my default option to boot:

title CentOS (2.6.18-308.13.1.el5)
        root (hd0,0)
        kernel /vmlinuz-2.6.18-308.13.1.el5 ro root=/dev/VolGroup00/LogVol00
        initrd /initrd-2.6.18-308.13.1.el5.img