Re: [libvirt] [Qemu-devel] Qemu migration with vhost-user-blk on top of local storage
-----Original Messages-----
From: "Stefan Hajnoczi" <stefanha(a)gmail.com>
Sent Time: 2019-01-09 20:42:58 (Wednesday)
To: wuzhouhui <wuzhouhui14(a)mails.ucas.ac.cn>
Cc: qemu-devel(a)nongnu.org, xieyongji(a)baidu.com, lilin24(a)baidu.com,
libvir-list(a)redhat.com, spdk(a)lists.01.org
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.
Anyway, following is full contents of XML:
<domain type='kvm'>
<name>wzh</name>
<uuid>a84e96e6-2c53-408d-986b-c709bc6a0e51</uuid>
<memory unit='MiB'>4096</memory>
<memoryBacking>
<hugepages/>
</memoryBacking>
<currentMemory unit='MiB'>4096</currentMemory>
<vcpu placement='static' cpuset='16-31'>2</vcpu>
<os>
<type arch='x86_64' machine='pc'>hvm</type>
<boot dev='hd'/>
</os>
<features>
<acpi/>
</features>
<clock offset='utc'>
<timer name='rtc' tickpolicy='catchup'/>
</clock>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>destroy</on_crash>
<devices>
<emulator>/data/wzh/x86_64-softmmu/qemu-system-x86_64</emulator>
<disk type='file' device='disk'>
<driver name='qemu' type='qcow2' cache='none'/>
<source file='/data/wzh/c74.qcow2'/>
<target dev='vda' bus='virtio'/>
<alias name='virtio-disk0'/>
</disk>
<disk type='vhost-user-blk' device='disk'>
<source type='unix' path='/var/tmp/lv0' mode='client'>
</source>
<target dev='vdb' bus='virtio'/>
<driver queues='4'/>
</disk>
<controller type='usb' index='0'>
<alias name='usb0'/>
</controller>
<controller type='pci' index='0' model='pci-root'>
<alias name='pci.0'/>
</controller>
<serial type='pty'>
<target port='0'/>
<alias name='serial0'/>
</serial>
<serial type='pty'>
<target port='1'/>
<alias name='serial1'/>
</serial>
<input type='tablet' bus='usb'>
<alias name='input0'/>
</input>
<input type='mouse' bus='ps2'/>
<graphics type='vnc' autoport='yes' listen='0.0.0.0'
keymap='en-us'>
<listen type='address' address='0.0.0.0'/>
</graphics>
<video>
<model type='cirrus' vram='9216' heads='1'/>
<alias name='video0'/>
</video>
</devices>
<seclabel type='none'/>
</domain>
> Does it means that qemu with spdk on top of local storage don't support
migration?
>
> QEMU: 2.12.1
> SPDK: 18.10
vhost-user-blk bypasses the QEMU block layer, so NBD storage migration
at the QEMU level will not work for the vhost-user-blk disk.
Stefan