virt-install with pool off glusterfs

Hi Guys, what can, is, wrong with that syntax of mine below? $ virt-install -n fcoskubermaster1 --virt-type kvm --os-variant fedora31 --graphics="none" --memory $((4*1024)) --disk="pool=gluster-VMs,size=10,path=/fcoskubermaster1.qcow2,backing_store=gluster://127.0.0.1/VMs/00-BACKing/fcoskubermaster1.qcow2" --network network=ovsbr0,model=virtio --accelerate --cpuset 3 --cpu host-model --vcpus 3 --import --qemu-commandline="-fw_cfg name=opt/com.coreos/config,file=/00.GLUSTER-mnt/VMs/fcos.ign" WARNING  fcoskubermaster1 may not be accessible by the hypervisor. You will need to grant the 'qemu' user search permissions for the following directories: [''] Starting install... ERROR    Couldn't create storage volume 'fcoskubermaster1': 'this function is not supported by the connection driver: storage pool does not support volume creation' Domain installation does not appear to have been successful. If it was, you can restart your domain by running:   virsh --connect qemu:///system?authfile=/etc/ovirt-hosted-engine/virsh_auth.conf start fcoskubermaster1 otherwise, please restart your installation. Basically what I hope to do is to have backing image and the actual one on a glusterfs volume, backing store in /00-BACKing and the image in / off that same gluster-VMs volume. many thanks, L.