Re: [Qemu-devel] [libvirt] Qemu migration with vhost-user-blk on top of local storage

[Peter Krempa]

On Wed, Jan 09, 2019 at 21:23:25 +0800, wuzhouhui wrote:
> > -----Original Messages-----
> > From: "Stefan Hajnoczi" <address@hidden>
> > Sent Time: 2019-01-09 20:42:58 (Wednesday)
> > To: wuzhouhui <address@hidden>
> > Cc: address@hidden, address@hidden, address@hidden, address@hidden, 
> > address@hidden
> > Subject: Re: [Qemu-devel] Qemu migration with vhost-user-blk on top of 
> > local storage
> > 
> > On Wed, Jan 09, 2019 at 06:23:42PM +0800, wuzhouhui wrote:
> > > Hi everyone,
> > > 
> > > I'm working qemu with vhost target (e.g. spdk), and I attempt to migrate 
> > > VM with
> > > 2 local storages. One local storage is a regular file, e.g. 
> > > /tmp/c74.qcow2, and
> > > the other is a malloc bdev that spdk created. This malloc bdev will 
> > > exported to
> > > VM via vhost-user-blk. When I execute following command:
> > > 
> > >   virsh migrate --live --persistent --unsafe --undefinesource 
> > > --copy-storage-all \
> > >      --p2p --auto-converge --verbose --desturi qemu+tcp://<uri>/system vm0
> > > 
> > > The libvirt reports:
> > > 
> > >   qemu-2.12.1: error: internal error: unable to execute QEMU command \
> > >     'nbd-server-add': Cannot find device=drive-virtio-disk1 nor \
> > >     node_name=drive-virtio-disk1
> > 
> > Please post your libvirt domain XML.
> 
> My libvirt is based on libvirt-1.1.1-29.el7, and add many patches to satisfy 
> our
> own needs, e.g. add support for vhost-user-blk. Post domain xml may not 
> useful.

So you added support for vhost-user-blk, but did not fix the
NBD migration code. You are on your own, sorry. We can't support
arbitrary downstream changes.

Please either upstream your patches or make sure to skip it for
vhost-user.

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