I am interested in how did you address the issues :) On Tue, Nov 6, 2012 at 7:42 PM, John Garbutt <John.Garbutt at citrix.com>wrote: > I am interested in following similar patterns with the XenServer SM work > (for NFS and local volumes). > We have the same issues around the hypervisor needing to be involved when > taking a snapshot (but with VHDs in our case). > https://blueprints.launchpad.net/cinder/+spec/xenapi-storage-manager > > We will try get back with some more concrete details once we sit down and > flesh out the blueprint a bit more. > We have done the prototyping to discover the issues now. > > John > > -----Original Message----- > From: Christoph Hellwig [mailto:hch at infradead.org] > Sent: 05 November 2012 11:38 AM > To: OpenStack Development Mailing List > Subject: Re: [openstack-dev] Island: Local Storage Volume Support for > Cinder > > On Fri, Nov 02, 2012 at 03:54:02PM -0700, Vishvananda Ishaya wrote: > > So we dealt with this exact issue when doing snapshots for instances. > > According to the libvirt folks, creating and/or deleting a snapshot > > using qemu-image while a disk is in use is not safe. > > It's indeed not. Creating snapshots of any image format while qemu is > running requires doing it using the qemu monitor. Note that this is the > exact same snapshot code that qemu-img would invoke, but doing it from qemu > means it is serialized vs I/O from the guest. > > > Unfortunately libvirt does not expose a reasonable method for > > snapshotting and extracting data from a live disk, so the only way to > > do this safely is to use qemu-monitor (or patch libvirt to expose the > > right interface). This is why the instance snapshot command in kvm is > > doing a managed save before snapshotting the vm. If we had a good way > > to do this it would greatly help the instance snapshot code as well. > > What do you mean with a managed save? > > > _______________________________________________ > OpenStack-dev mailing list > OpenStack-dev at lists.openstack.org > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > > _______________________________________________ > OpenStack-dev mailing list > OpenStack-dev at lists.openstack.org > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > -- Rongze Zhu - 朱荣泽 Twitter: @metaxen Blog: http://blog.csdn.net/metaxen Weibo: http://weibo.com/metaxen Website: Try Free OpenStack in http://www.stacklab.org<http://stacklab.org> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.openstack.org/pipermail/openstack-dev/attachments/20121108/35735122/attachment.html>