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Upstream qemu 1.3 is adding two new monitor commands, 'drive-mirror' and 'block-job-complete'[1], which can drive live block copy and storage migration. [Additionally, RHEL 6.3 had backported an earlier version of most of the same functionality, but under the names '__com.redhat_drive-mirror' and '__com.redhat_drive-reopen' and with slightly different JSON arguments, and has been using patches similar to these upstream patches for several months now.] The libvirt API virDomainBlockRebase as already committed for 0.9.12 is flexible enough to expose the basics of block copy, but some additional features in the 'drive-mirror' qemu command, such as setting error policy, setting granularity, or using a persistent bitmap, may later require a new libvirt API virDomainBlockCopy. I will wait to add that API until we know more about what qemu 1.3 will finally provide. This patch caters only to the upstream qemu 1.3 interface, although I have proven that the changes for RHEL 6.3 can be isolated to just qemu_monitor_json.c, and the rest of this series will gracefully handle either interface once the JSON differences are papered over in a downstream patch. For consistency with other block job commands, libvirt must handle the bandwidth argument as MiB/sec from the user, even though qemu exposes the speed argument as bytes/sec; then again, qemu rounds up to cluster size internally, so using MiB hides the worst effects of that rounding if you pass small numbers. [1]https://lists.gnu.org/archive/html/qemu-devel/2012-10/msg04123.html * src/qemu/qemu_capabilities.h (QEMU_CAPS_DRIVE_MIRROR) (QEMU_CAPS_DRIVE_REOPEN): New bits. * src/qemu/qemu_capabilities.c (qemuCaps): Name them. * src/qemu/qemu_monitor_json.c (qemuMonitorJSONCheckCommands): Set them. (qemuMonitorJSONDriveMirror, qemuMonitorDrivePivot): New functions. * src/qemu/qemu_monitor_json.h (qemuMonitorJSONDriveMirror) (qemuMonitorDrivePivot): Declare them. * src/qemu/qemu_monitor.c (qemuMonitorDriveMirror) (qemuMonitorDrivePivot): New passthroughs. * src/qemu/qemu_monitor.h (qemuMonitorDriveMirror) (qemuMonitorDrivePivot): Declare them.
LibVirt : simple API for virtualization
Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.
Daniel Veillard <veillard@redhat.com>