On Wed, Feb 15, 2017 at 03:14:19PM +0000, Stefan Hajnoczi wrote: > On Mon, Feb 13, 2017 at 05:46:19PM +0200, Maor Lipchuk wrote: > > I was wondering if that is possible to provide a new API that > > estimates the size of > > qcow2 image converted from a raw image. We could use this new API to > > allocate the > > size more precisely before the convert operation. > > > [...] > > We think that the best way to solve this issue is to return this info > > from qemu-img, maybe as a flag to qemu-img convert that will > > calculate the size of the converted image without doing any writes. > > Sounds reasonable. qcow2 actually already does some of this calculation > internally for image preallocation in qcow2_create2(). > > Let's try this syntax: > > $ qemu-img query-max-size -f raw -O qcow2 input.raw > 1234678000 > > As John explained, it is only an estimate. But it will be a > conservative maximum.
This forces you to have an input file. It would be nice to be able to get the same information by merely giving the desired capacity e.g $ qemu-img query-max-size -O qcow2 20G Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://entangle-photo.org -o- http://search.cpan.org/~danberr/ :|
