virsh requires btrfs to create dir based pool
Following instructions here to create a directory based pool : https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/virtualization_administration_guide/sect-virtualization-storage_pools-creating-local_directories-virsh
virt:/home/qemu# mkdir /guest_images
virt:/home/qemu# chown root:root /guest_images
virt:/home/qemu# chmod 700 /guest_images
virt:/home/qemu# ls -la /guest_images
total 8
drwx------ 2 root root 4096 Sep 2 18:52 .
drwxr-xr-x 23 root root 4096 Sep 2 18:52 ..
virt:/home/qemu# virsh pool-list --all
Name State Autostart
--------------------------------------
default active no
guest_images inactive no
qemu active yes
virt:/home/qemu# virsh pool-build guest_images
error: Failed to build pool guest_images
error: unable to control COW flag on '/guest_images', not btrfs: Function not implemented
virt:/home/qemu# virsh --version
6.6.0
Fair enough if COW needs BTRFS, but if I don't need COW, it would be nice to be able to disable it somehow. There seems to be no option to do so...
Others facing the same problem : https://www.reddit.com/r/openSUSE/comments/ibxcs3/unable_to_create_new_pool_unable_to_control_cow/ https://unix.stackexchange.com/questions/604606/can-t-create-vm-in-virt-manager-due-to-unavailable-storage-device