Destination host emulator is different. Cannot be migrated

[skyshe]

Hi

host1：
libvirtd -V
libvirtd (libvirt) 4.0.0

host2：
libvirtd -V
libvirtd (libvirt) 4.0.0

host1：
cat /etc/issue
Ubuntu 18.04.6 LTS \n \l
host2：
cat /etc/issue
Ubuntu 18.04.6 LTS \n \l

I installed the ubuntu 18.04 system on 2 physical hosts, and both deployed libvirtd
Host 1 deploys webvirtcloud and libvirtd, and they are used normally. Host 2 only deploys libvirtd to connect to host 1's webvirtcloud via TCP, but an error is reported when using the migration function. Destination host emulator is different. Cannot be migrated

What could be the cause of this, and what should I do?

thanks

err imges：

[catborise]

qemu-kvm version is important. libvirt version has minor effect.
run virsh version command to see difference…

[skyshe]

What puzzles me is that they are not different。

host1：
virsh version
Compiled against library: libvirt 4.0.0
Using library: libvirt 4.0.0
Using API: QEMU 4.0.0
Running hypervisor: QEMU 2.11.1

host2：
virsh version
Compiled against library: libvirt 4.0.0
Using library: libvirt 4.0.0
Using API: QEMU 4.0.0
Running hypervisor: QEMU 2.11.1

[catborise]

Interesting, can you please check it if it working on cli with;
virsh migrate --live --persistent --undefinesource --verbose <vm name> qemu+ssh://<user@destinationip>/system

[skyshe]

When I execute it for the first time, it prompts that the storage file does not exist. When I manually scp the storage file to host 2, it prompts an error again.

err1
virsh migrate --live --persistent --undefinesource --verbose vm1 qemu+ssh://172.16.0.2/system
error: Cannot access storage file '/kvm/vfs/vm1.qcow2' (as uid:64055, gid:114): No such file or directory

virsh migrate --live --persistent --undefinesource --verbose vm1 qemu+tcp://172.16.0.2/system
error: Cannot access storage file '/kvm/vfs/vm1.qcow2' (as uid:64055, gid:114): No such file or directory

err2
virsh migrate --live --persistent --undefinesource --verbose vm1 qemu+tcp://172.16.0.2/system
error: Unable to resolve address 'andy' service '49152': Temporary failure in name resolution

virsh migrate --live --persistent --undefinesource --verbose vm1 qemu+ssh://172.16.0.2/system
error: Unable to resolve address 'andy' service '49152': Temporary failure in name resolution

[catborise]

first of all, check your services for libvirt daemon. It should be in listening mode. (https://askubuntu.com/questions/423425/i-cant-use-libvirt-with-listen-tcp)

It would be nice to have NFS storage to keep vm disks for migration. if you do not have it then you should look at this article(https://hgj.hu/live-migrating-a-virtual-machine-with-libvirt-without-a-shared-storage/)

[skyshe]

First of all, thank you for your enthusiastic answer.

The libvirt daemon service of my host 2 is running. TCP connection is in listening mode。

netstat -lntp
(Not all processes could be identified, non-owned process info
will not be shown, you would have to be root to see it all.)
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 127.0.0.1:6010 0.0.0.0:* LISTEN -
tcp 0 0 0.0.0.0:16509 0.0.0.0:* LISTEN -
tcp 0 0 0.0.0.0:16510 0.0.0.0:* LISTEN -
tcp 0 0 0.0.0.0:5900 0.0.0.0:* LISTEN -
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN -
tcp 0 0 192.168.100.1:53 0.0.0.0:* LISTEN -
tcp 0 0 127.0.0.53:53 0.0.0.0:* LISTEN -
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN -
tcp6 0 0 ::1:6010 :::* LISTEN -
tcp6 0 0 :::80 :::* LISTEN -
tcp6 0 0 240c::1:53 :::* LISTEN -
tcp6 0 0 fe80::5054:ff:fedd:4:53 :::* LISTEN -
tcp6 0 0 :::22 :::* LISTEN -

#systemctl status libvirt-bin.service
● libvirtd.service - Virtualization daemon
Loaded: loaded (/lib/systemd/system/libvirtd.service; enabled; vendor preset: enabled)
Active: active (running) since Thu 2021-10-14 18:23:21 CST; 22h ago
Docs: man:libvirtd(8)
https://libvirt.org
Main PID: 2529 (libvirtd)
Tasks: 27 (limit: 32768)
CGroup: /system.slice/libvirtd.service
├─2089 /usr/sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/NAT.conf --leasefile-ro --dhcp-script=/usr/lib/libvirt/libvirt_leaseshelper
├─2090 /usr/sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/NAT.conf --leasefile-ro --dhcp-script=/usr/lib/libvirt/libvirt_leaseshelper
├─2529 /usr/sbin/libvirtd -l
└─5034 qemu-system-x86_64 -enable-kvm -name guest=vyos,debug-threads=on -S -object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-1-vyos/master-key.aes -machine pc-i440fx-2.11,accel=kvm,usb=off,
#systemctl status libvirtd.service.service
Unit libvirtd.service.service could not be found.
andy@andy:~$ systemctl status libvirtd.service
● libvirtd.service - Virtualization daemon
Loaded: loaded (/lib/systemd/system/libvirtd.service; enabled; vendor preset: enabled)
Active: active (running) since Thu 2021-10-14 18:23:21 CST; 22h ago
Docs: man:libvirtd(8)
https://libvirt.org
Main PID: 2529 (libvirtd)
Tasks: 27 (limit: 32768)
CGroup: /system.slice/libvirtd.service
├─2089 /usr/sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/NAT.conf --leasefile-ro --dhcp-script=/usr/lib/libvirt/libvirt_leaseshelper
├─2090 /usr/sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/NAT.conf --leasefile-ro --dhcp-script=/usr/lib/libvirt/libvirt_leaseshelper
├─2529 /usr/sbin/libvirtd -l

[skyshe]

[skyshe]

The current problems encountered are:

1. Migrate in the web console and report an error Destination host emulator is different. Cannot be migrated

2. Operation in cli reports an error, error: Unable to resolve address'andy' service '49152': Temporary failure in name resolution

[catborise]

sorry for late answer. webvirtcloud is an interface, nothing more. if you cannot migrate with "virsh migrate" command, webvirtcloud cannot also.
you should fix it with libvirt configuration.
"Operation in cli reports an error, error: Unable to resolve address'andy' service '49152': Temporary failure in name resolution" there should not be any service with named andy. may be it is related with firewall: https://stackoverflow.com/questions/55396045/live-migrate-kvm-vm-failed-with-tcp-connection-in-ubuntu

[skyshe]

Hi

First of all thank you for your reply,

Currently, two-way migration under cli is normal,

but migration under WebVirtCloud still prompts an error:（Destination host emulator is different. Cannot be migrated）

At present, WebVirtCloud reports an error during the migration operation and still can't find a solution.

host1
virsh migrate --live --persistent --verbose 5 qemu+ssh://172.16.0.2/system
Migration: [100 %]
virsh migrate --live --persistent --verbose 7 qemu+tcp://172.16.0.2/system
Migration: [100 %]

host2
virsh migrate --live --persistent --verbose 18 qemu+ssh://172.16.0.1/system
Migration: [100 %]
virsh migrate --live --persistent --verbose 17 qemu+tcp://172.16.0.1/system
Migration: [100 %]

[skyshe]

I now use the virsh migrate command, including the use of virt-manager UI to connect to the host and the migration is normal, but the migration operation is still not possible in webvirtcloud, every time it is prompted: Destination host emulator is different. Cannot be migrated

sudo virsh migrate --live --persistent --verbose vm1.xxx.com qemu+tcp://172.16.0.1/system
Migration: [100 %]

[catborise]

may be the problem is related with host adding method. one host added with "localhost" the other is with ip.

can you please add both hosts with IP adress, then try it again.

[skyshe]

Currently, all TCP connections are used in WebVirtCloud.

connect qemu+tcp://172.16.0.1/system
connect qemu+tcp://172.16.0.2/system

node1:~$ virsh version
Compiled against library: libvirt 4.0.0
Using library: libvirt 4.0.0
Using API: QEMU 4.0.0
Running hypervisor: QEMU 2.11.1

node2:~$ virsh version
Compiled against library: libvirt 4.0.0
Using library: libvirt 4.0.0
Using API: QEMU 4.0.0
Running hypervisor: QEMU 2.11.1

[catborise]

there must be a glitch we should detect:
can you please check emulator on host overview page to see if they are same on both host

[skyshe]

The host overview page and virsh version show the same version

node1

node2