[virt-tools-list] Is the default of "format" raw? (virt-install)

Chen Hanxiao chenhanxiao at cn.fujitsu.com
Thu Mar 13 05:14:44 UTC 2014

> -----Original Message-----
> From: virt-tools-list-bounces at redhat.com
> [mailto:virt-tools-list-bounces at redhat.com] On Behalf Of Peng Yu
> Sent: Thursday, March 13, 2014 12:39 PM
> To: virt-tools-list at redhat.com
> Subject: [virt-tools-list] Is the default of "format" raw? (virt-install)
> Hi,
> `man virt-install` says the following. But it is not clear to me what
> format is used if it is not specified explicitly. Does anybody know?
> Should this be documented?

What version do you use?
In upstream, I found this in virt-install man page:

"If not specified when creating file images, this will default to 'qcow2'."

And commit in git repository could be founded at:


> Also, how to check what the format is of an image file? Thanks.

You could try command "file"
#file NAME
qcow2: QEMU QCOW Image (v2), 1048576 bytes

> format
>   Image format to be used if creating managed storage. For file
>   volumes, this can be 'raw', 'qcow2', 'vmdk', etc. See format
>   types in <http://libvirt.org/storage.html> for possible values.
>   This is often mapped to the driver_type value as well.
>   With libvirt 0.8.3 and later, this option should be specified if
>   reusing an existing disk image, since libvirt does not autodetect
>   storage format as it is a potential security issue. For example,
>   if reusing an existing qcow2 image, you will want to specify
>   format=qcow2, otherwise the hypervisor may not be able to read
>   your disk image.
> --
> Regards,
> Peng
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