KVM Disk Formats: Portability

dean asked:

I have recently begun experimenting with the KVM virtualization infrastructure. After deployment, I used virt-manager running on a management computer to build my first guest. I notice that, by default, the resulting virtual machine is in the RAW format.

From what I understand, it is possible to create virtual disks of various formats. (http://www.linux-kvm.org/page/FAQ#What_virtual_disk_formats_can_KVM_use.3F).

My questions are:
1) What format is generally considered most portable? (i.e. moving to a new virtualization platform/hypervisor)

2) Is is possibly to specify format during virtual machine creation in virt-manager, if so, how?

3) Can anyone suggest a more feature rich management tool besides virt-manager?

My answer:


virt-manager creates raw disk images by default. These are the most portable, since any hypervisor known to man can deal with them. If you create one as a file on disk, it will have the .img extension.

If you want to choose a different format, then when adding storage, choose “Select managed or other existing storage”, then click Browse. On the next screen select a storage pool, click New Volume, and you can create a volume in any of a variety of formats.

Storage configuration

As for other management tools, you have a huge variety, everything from OpenStack to the virsh command line tool. You’ll have to do your own shopping here….


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