On 10/09/2014 03:01 PM, Vasiliy Tolstov wrote: > I have lvm based (thin pool) storage on local disks. I need to move > vps from one vg on one disk to another. Does it possible to migrate to > localhost with blockcopy migration to another vg? > > I'm understand that i can move lv from one vg to another, but i don't need that. So to restate and make sure I understand what you are asking, you have a running guest that you want to leave running, where the guest is currently using /path/to/vg1/lv1 (remote), and where you want to alter it to use /path/to/vg2/lv2 (local). If I'm correct, libvirt live block migration can do that; however, it requires that your domain be temporarily marked transient (due to the fact that the operation cannot be efficiently restarted; we hope to lift that restriction when some future qemu gives us better control over persistent dirty bitmaps). virsh dumpxml $dom > dom.xml virsh undefine $dom virsh blockcopy $dom /path/to/vg1/lv1 /path/to/vg2/lv2 --verbose --pivot edit dom.xml to change /path/to/vg1/lv1 to /path/to/vg2/lv2 virsh define dom.xml which will use qemu to copy the entire disk contents into a new location (that third step is potentially slow). Note that with new enough libvirt and qemu, you can get even fancier and faster, by using external commands that can move an lv between vgs with minimal copying time (I don't personally know lvm commands well enough to say what the sequence is, only that I suspect it can be done without the overhead of copying the entire lv by instead adjusting bookkeeping of which vg owns the lv): virsh snapshot-create-as $dom --no-metadata --disk-only \ --diskspec vda,file=/path/to/wrapper1.qcow2 work your magic to move/copy vg1/lv1 into vg2/lv2 qemu-img create -f qcow2 \ -o backing_file=/path/to/vg2/lv2,backing_fmt=qcow2 \ /path/to/wrapper2.qcow2 virsh dumpxml $dom > dom.xml virsh undefine $dom virsh blockcopy $dom vda --reuse-external \ /path/to/wrapper2.qcow2 --shallow --verbose --pivot edit dom.xml to change wrapper1 to wrapper2 virsh define dom.xml virsh blockcommit $dom vda --pivot --shallow --verbose -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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