On Tue, May 17, 2016 at 6:01 PM, Richard W.M. Jones <[email protected]> wrote:
> On Tue, May 17, 2016 at 05:53:31PM +0300, Yaniv Kaul wrote: > > On Tue, May 17, 2016 at 5:48 PM, Richard W.M. Jones <[email protected]> > > wrote: > > > > > On Tue, May 17, 2016 at 03:41:53PM +0100, Richard W.M. Jones wrote: > > > > On Tue, May 17, 2016 at 05:15:57PM +0300, Yaniv Kaul wrote: > > > > > When creating qcow2 images using virt-builder, is there a way to > > > specify > > > > > the qcow2 preallocation, as possible with qemu-img create -o > > > > > preallocation=metada , for example? > > > > > > > > No .. but .. it does default to preallocation=metadata provided that > > > > the output format is qcow2: > > > > > > > > > > > > https://github.com/libguestfs/libguestfs/blob/master/builder/builder.ml#L582-L585 > > > > > > I should say this only applies when the image needs to be resized > > > (ie. you supply a --size parameter which != the size of the template), > > > AND if the resize is the final step that the planner comes up with. > > > > > > > > > > https://rwmj.wordpress.com/2013/12/14/writing-a-planner-to-solve-a-tricky-programming-optimization-problem/ > > > > > > Oh. I don't think there[1] is any need to resize in the code, it's just > > directly using the templates virt-builder uses, AFAIK. > > The problem is: Suppose the input template is already qcow2, and the > output format requested is qcow2, virt-builder will just copy the > input to the output and not do any preallocation. > I expect the input images virt-builder uses (by default) to have preallocation=metadata. (Then again, I expected RHEL, CentOS and Fedora cloud images to be qcow2v3 - and they aren't - just plain 0.1 compat level). Y. > > To force a particular preallocation mode for the output image, an > extra step might be required, and that would have to be modelled in > the planner. > > The blog post above is quite interesting. Though Wordpress in its > infinite wisdom decided to break the diagram. You can see the diagram > here: http://oirase.annexia.org/rwmj.wp.com/strips.svg > > Rich. > > > > > [1] > > > https://github.com/lago-project/lago-images/blob/inital-setup/bin/build.py > > > > > > > > > > In the general case implementing this is more complicated. I think it > > > would require another planner transition. > > > > > > Rich. > > > > > > -- > > > Richard Jones, Virtualization Group, Red Hat > > > http://people.redhat.com/~rjones > > > Read my programming and virtualization blog: http://rwmj.wordpress.com > > > virt-top is 'top' for virtual machines. Tiny program with many > > > powerful monitoring features, net stats, disk stats, logging, etc. > > > http://people.redhat.com/~rjones/virt-top > > > > > -- > Richard Jones, Virtualization Group, Red Hat > http://people.redhat.com/~rjones > Read my programming and virtualization blog: http://rwmj.wordpress.com > virt-df lists disk usage of guests without needing to install any > software inside the virtual machine. Supports Linux and Windows. > http://people.redhat.com/~rjones/virt-df/ >
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