On Sep 18, 2013, at 4:50 PM, Josh Durgin <josh.dur...@inktank.com> wrote:
> On 09/18/2013 07:14 AM, Thierry Carrez wrote: >> Mike Perez wrote: >>> Currently in Havana development, RBD as ephemeral storage has serious >>> stability >>> and performance issues that makes the Ceph cluster a bottleneck for using an >>> image as a source. >>> [...] >> >> This comes up a bit late, and the current RC bugs curves[1] really do >> not encourage me to add more distraction for core reviewers. >> >> The only way I could be fine with this would be for the performance >> issue to actually be considered a bug (being so slow you can't really >> use it without the fix), *and* the review being very advanced and >> consensual that the distraction is minimal. >> >> Could you quantify the performance issue, and address Zhi Yan Liu's >> comments ? > > In terms of performance, consider an image that's already cached on > the hypervisor host. Using the libvirt_images_type=rbd, the locally > cached copy is imported via the 'rbd import' command. This is a very > slow operation, which ended up taking upwards of 15 minutes in my > tests. > > Using libvirt_images_type=qcow2, this takes roughly 0.2 seconds. > > If the image was not already cached locally, it would have to be > downloaded from glance, which would take the same amount of time > regardless of libvirt_images_type or glance backend. > > The proposed patch avoids downloading from glance and uploading to > rbd, and results in similar times to qcow2 without requiring the image > to be cached locally. > > Josh Its too bad that the timing is so bad because this seems like a really useful feature. It might be worth it merge a patch into icehouse ASAP and see if you can get the distros on board with backporting the patch. Vish _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
