On Thu, Sep 01, 2011 at 02:14:23PM +0100, Daniel P. Berrange wrote: > On Wed, Aug 31, 2011 at 09:31:58PM +0800, Osier Yang wrote: > > Upstream QEMU introduced online block resizing to resize the > > block device when domain is running since commit 6d4a2b3a4795. > > It simply reuses existing "bdrv_truncate" method which is used > > by "qemu-img" to resize the images. This means it supports to > > resize all the format that "qemu-img resize" supports. E.g. > > qcow2, raw, qed, qcow, etc. (NB, it doesn't support to shrink > > size of qcow2 image, and QEMU reports "An undefined error > > has ocurred" in this case). > > > > For block device of virtio bus, the guest can update the device > > size automatically, needs kernel support, since kernel-2.6.32-117: > > > > http://patchwork.usersys.redhat.com/patch/33040/ > > > > For block device of SCSI bus, one needs to execute command like > > below in the guest (linux) to update the size: > > > > % echo > /sys/class/scsi_device/0:0:0:0/device/rescan > > > > For block device of IDE bus, seems there is no way to let guest > > update the size after resizing. > > Your API proprosal looks reasonable, but unfortunately the QEMU > command 'block_resize' is either broken, or incomplete since it > does not have a way to notify the guest that a block device has > been resized, independantly of actually resizing the host file. > This is required in order for guest disk resize to work on LVM, > SCSI, iSCSI, etc block devices, since QEMU cannot itself do a > resize of the block devices. The resize has to be done either > by libvirt using host commands, or by the SAN administrator on > the remote storage appliance. > > IMHO, we should not commit to the libvirt API design, until we > can get confirmation from QEMU about whether they will fix the > block_resize command to work for block devices, or add a new > command for just notifying guests of external block device > resizes See this thread... http://lists.nongnu.org/archive/html/qemu-devel/2011-09/msg00068.html Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list