On Tue, Jun 14, 2011 at 11:53:32AM +0100, Paul Mansfield wrote: > On 08/06/11 17:53, Gary Scarborough wrote: > > I guess the difference is that on the qcow2 files, the full(maximum) > > size is not showing up. > > > > qemu-img info junk.img shows: > > > > image: junk.img > > file format: qcow2 > > virtual size: 10G (10737418240 bytes) > > disk size: 140K > > cluster_size: 65536 > > I would guess the "disk size" is the contained file system, not > including the qcow2 "wrapper" overhead > > > ls -lash junk.img shows: > > > > 140K -rw-r--r-- 1 root root 193K Jun 8 11:11 junk.img > > so the overhead of qcow2 container is ?53K. does this grow as the > virtual disk fills up?
qcow2 uses a two-level directory. The second level is not allocated until required unless you selected the "preallocation" option when creating the disk. So if you didn't use "-o preallocation" then yes this overhead can grow as more disk blocks get allocated. By the way, we found that preallocation is faster. Mark wrote extensive documentation on qcow2 here: http://people.gnome.org/~markmc/qcow-image-format.html Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into Xen guests. http://et.redhat.com/~rjones/virt-p2v _______________________________________________ virt-tools-list mailing list [email protected] https://www.redhat.com/mailman/listinfo/virt-tools-list
