Live Migration fails on 4.14

Community Support
1

Hi,

Live migration is failing, I’ve received an error:

Mon Sep 28
18:47:03 2015 [Z0][VMM][E]: migrate: Command "virsh --connect
qemu:///system migrate --live one-94 qemu+ssh://sigcloud01/system"
failed: error: Cannot recv data: Host key verification failed.: Connection
reset by peer

The problem was the nodes where not sharing their public key, once that resolved we’re facing another error:

Mon Sep 28 19:27:38 2015 [Z0][VMM][E]: migrate: Command “virsh --connect qemu:///system migrate --live one-94 qemu+ssh://sigcloud01/system” failed: error: No se puede obtener interfaz MTU en ‘br0’: No existe el dispositivo

The problem was br0 interface was not created.

Now, the error is:
[Z0][VMM][E]: migrate: Command “virsh --connect qemu:///system migrate --live one-90 qemu+ssh://sigcloud01/system” failed: error: error interno el proceso ha finalizado mientras se conectaba con el monitor: qemu-kvm: -M pc-i440fx-rhel7.0.0: Unsupported machine type
[Z0][VMM][I]: Use -M ? to list supported machines!

Running on target host /usr/libexec/qemu-kvm -M ?
Supported machines are:
pc RHEL 6.6.0 PC (alias of rhel6.6.0)
rhel6.6.0 RHEL 6.6.0 PC (default)
rhel6.5.0 RHEL 6.5.0 PC
rhel6.4.0 RHEL 6.4.0 PC
rhel6.3.0 RHEL 6.3.0 PC
rhel6.2.0 RHEL 6.2.0 PC
rhel6.1.0 RHEL 6.1.0 PC
rhel6.0.0 RHEL 6.0.0 PC
rhel5.5.0 RHEL 5.5.0 PC
rhel5.4.4 RHEL 5.4.4 PC
rhel5.4.0 RHEL 5.4.0 PC

Running on target host /usr/libexec/qemu-kvm -M ?
Supported machines are:
none empty machine
pc RHEL 7.0.0 PC (i440FX + PIIX, 1996) (alias of pc-i440fx-rhel7.0.0)
pc-i440fx-rhel7.0.0 RHEL 7.0.0 PC (i440FX + PIIX, 1996) (default)
rhel6.6.0 RHEL 6.6.0 PC
rhel6.5.0 RHEL 6.5.0 PC
rhel6.4.0 RHEL 6.4.0 PC
rhel6.3.0 RHEL 6.3.0 PC
rhel6.2.0 RHEL 6.2.0 PC
rhel6.1.0 RHEL 6.1.0 PC
rhel6.0.0 RHEL 6.0.0 PC

The host source is CentOS 7, the target host is CentOS 6.7, is impossible to live migrate a VM from CentOS 7 to CentOS 6???

Thank you.

2

When using different distribution versions in your hosts you can do two things:

  • Separate the hosts in clusters, for example one for CentOS 6 and other for CentOS 7
  • If you still want to do migrations between those hosts set OS/MACHINE value

Libvirt has a series of machine types defined as you’ve shown. These are there as in new releases the machine configuration may support things that older versions can not. For example drivers, chipsets, features, etc. To make it work set a machine that is supported in all your hypervisors.

3

Thank you Javi, finally we’ve upgraded the CentOS 6 host to CentOS 7, and live migration is working fine now.