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 Chapter 7. Converting between image formats

Converting images from one format to another is generally straightforward.

 qemu-img convert: raw, qcow2, QED, VDI, VMDK, VHD

The qemu-img convert command can do conversion between multiple formats, including qcow2, QED, raw, VDI (VirtualBox), VHD (Hyper-V), and VMDK (VMware).

Table 7.1. qemu-img format strings
Image format Argument to qemu-img
qcow2 (KVM, Xen) qcow2
QED (KVM) qed
raw raw
VDI (VirtualBox) vdi
VHD (Hyper-V) vpc
VMDK (VMware) vmdk

This example will convert a raw image file named centos7.img to a qcow2 image file.

$ qemu-img convert -f raw -O qcow2 centos7.img centos7.qcow2

Run the following command to convert a VMDK image file to a raw image file.

$ qemu-img convert -f vmdk -O raw centos7.vmdk centos7.img

Run the following command to convert a VMDK image file to a qcow2 image file.

$ qemu-img convert -f vmdk -O qcow2 centos7.vmdk centos7.qcow2


The -f format flag is optional. If omitted, qemu-img will try to infer the image format.

When converting an image file with Windows OS, ensure the virtio driver is installed. Otherwise, you will get a blue screen of death or BSOD when launching the image due to lack of the virtio driver. Another option is to set the image properties as below when you update the image in glance to avoid this issue, but it will reduce performance significantly.

$ glance image-update --property hw_disk_bus='ide' image_id

 VBoxManage: VDI (VirtualBox) to raw

If you've created a VDI image using VirtualBox, you can convert it to raw format using the VBoxManage command-line tool that ships with VirtualBox. On Mac OS X, and Linux, VirtualBox stores images by default in the ~/VirtualBox VMs/ directory. The following example creates a raw image in the current directory from a VirtualBox VDI image.

$ VBoxManage clonehd ~/VirtualBox\ VMs/fedora21.vdi fedora21.img --format raw
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