It sounds like a useful feature, and there are a growing number of touch points for libvirt assisted cinder features. A summit session to discuss how that interface should work (hopefully get a few nova folks there as well, the interface has two ends) might be a good idea
On 27 March 2014 16:15, Trump.Zhang <zhangleiqi...@gmail.com> wrote: > Online-extend volume feature aims to extend a cinder volume which is in-use, > and make the corresponding disk in instance extend without stop the > instance. > > > The background is that, John Griffith has proposed a BP ([1]) aimed to > provide an cinder extension to enable extend of in-use/attached volumes. > After discussing with Paul Marshall, the assignee of this BP, he only focus > on OpenVZ driver currently, so I want to take the work of libvirt/qemu based > on his current work. > > A volume can be extended or not is determined by Cinder. However, if we want > the capacity of corresponding disk in instance extends, Nova must be > involved. > > Libvirt provides "block_resize" interface for this situation. For QEMU, the > internal workflow for block_resize as follows: > > 1) Drain all IO of this disk from instance > 2) If the backend of disk is a normal file, such as raw, qcow2, etc, qemu > will do the *extend* work > 3) If the backend of disk is block device, qemu will first judge if there is > enough free space on the device, if only so, it will do the *extend* work. > > So I think the "online-extend" volume will need QEMU Assisted, which is > simlar to BP [2]. > > Do you think we should introduce this feature? > > [1] > https://blueprints.launchpad.net/cinder/+spec/inuse-extend-volume-extension > [2] https://blueprints.launchpad.net/nova/+spec/qemu-assisted-snapshots > > _______________________________________________ > OpenStack-dev mailing list > OpenStack-dev@lists.openstack.org > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > -- Duncan Thomas _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev