https://listman.redhat.com/archives/virt-tools-list/2014-March/msg00110.html

On 03/13/2014 12:53 AM, Peng Yu wrote:
> Hi, > > The following command gives me the error in the title. Does anybody > know how to specify the file format? Thanks. > > sudo virt-install -n web_devel_qcow2_name -r 4096 --disk > path=/tmp/web_devel_qcow2,bus=virtio,size=1,format=qcow2 -c > ~/iso/ubuntu-13.10-server-amd64.iso --network bridge=br0,model=virtio > --graphics vnc,listen=0.0.0.0 --noautoconsole -v > > https://www.suse.com/documentation/sles11/singlehtml/book_kvm/book_kvm.html#tip.libvirt.config.pci.virsh.managed > > Also, I found the following explanation on the above page. But I don't > quite understand it. Does "managed" only applies to PCI devices (hence > not disk)? Thanks.  No, managed in this case means that /tmp is not a libvirt storage pool, and
therefor we don't know how to create a qcow2 disk image (it's only supported
through libvirt's storage APIs).

The latest release of virt-install 1.0.0 will turn /tmp into a storage pool
automatically. To do it manually, you can do

virsh pool-define-as --name tmppool --type dir --target /tmp
virsh pool-start tmppool

- Cole