On Thu, Sep 25, 2014 at 07:56:09PM +0530, Kashyap Chamarthy wrote:
> This notes is based on an IRC conversation with Eric Blake, to have
> efficient non-shared storage live migration. Thought I'd post my notes
> here before I forget. Please review and spot if there are any
> inaccuracies.
Noting a couple of things I missed. . .
> Procedure
> ---------
>
> (1) Starting from disk A, create a snapshot A <- A':
>
> $ virsh snapshot-create-as \
> --domain f20vm snap1 snap1-desc \
> --diskspec hda,file=/export/vmimages/A'.qcow2 \
> --disk-only --atomic
Before performing a live blockcopy, make the domain transient (as
persistent dirty bitmap support is yet to arrive in QEMU).
Take backup of the guest XML:
$ virsh dumpxml f20vm > /var/tmp/f20vm.xml
Undefine the running guest, thus turning it to a transient guest:
$ virsh undefine f20vm
> (2) Background copy of A to B:
>
> $ virsh blockcopy \
> --domain vm1 vda /export/vmimages/B.qcow2 \
> --wait --verbose --shallow \
> --finish
>
> (3) Create an empty B' with backing file B:
>
> $ qemu-img create -f qcow2 -b B.qcow2 \
> -o backing_fmt=qcow2 B'.qcow2
>
> [or]
>
> $ virsh vol-create-as default B'.qcow2 1G \
> --format qcow2 \
> --backing-vol B.qcow2 --backing-vol-format qcow2
>
> (4) Do a shallow blockcopy of A' to B':
>
> $ virsh blockcopy \
> --domain vm1 vda /export/vmimages/B'.qcow2 \
> --wait --verbose --shallow \
> --finish
Since the a chain was already created in step (3), I should have used
'--reuse-external' flag at this shallow blockcopy.
>
> (5) Then live shallow commit of B:
>
> $ virsh blockcommit \
> --domain f20vm vda \
> --wait --verbose --shallow \
> --pivot --active --finish
> Block Commit: [100 %]
> Successfully pivoted
>
--
/kashyap
--
libvir-list mailing list
libvir-list@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/libvir-list