[libvirt-users] Why are virsh vol-upload/vol-download so slow?

I was interested in using 'virsh vol-upload' and 'virsh vol-download', rather than mucking about directly with the filesystem. But while simply copying the image is relatively quick: # ls -l /var/lib/libvirt/images/centos-7-cloud.qcow2 -rw-r--r--. 1 qemu qemu 1004994560 Apr 15 2015 centos-7-cloud.qcow2 # time cp /var/lib/libvirt/images/centos-7-cloud.qcow2 /tmp/myimage.qcow2 real 0m10.829s user 0m0.024s sys 0m1.668s Trying to do the same thing with `virsh vol-download` is glacial: # time virsh vol-download --pool default centos-7-cloud.qcow2 /tmp/myimage.qcow2 I killed it after 10 minutes: real 10m20.775s user 10m19.451s sys 0m1.887s After which is was about halfway through: # ls -l /tmp/myimage.qcow2 -rw-r--r--. 1 root root 564920248 Mar 4 11:11 /tmp/myimage.qcow2 What is up with that? -- Lars Kellogg-Stedman <lars(a)redhat.com&gt; | larsks @ {freenode,twitter,github} Cloud Engineering / OpenStack | http://blog.oddbit.com/