Hypervisor release
A live virtual server migration preserves the machine type of the virtual server.
The libvirt-internal configuration is not changed, that is, the machine type still reflects the hypervisor release of the source host. Newer hypervisor releases are compatible with earlier versions.
However, if you try to migrate a virtual server to a destination host with an earlier hypervisor release than the currently reflected machine type, you need to explicitly specify this earlier machine type in the virtual server definition before the migration.
- Before the migration, the virtual server is running on
the source host with a hypervisor release based on
QEMU 5.0. The virtual server's machine
type is s390-ccw-virtio-5.0.
- After the migration, the virtual server is running on the
destination host with a hypervisor release based on
QEMU 6.2. The virtual server's machine
type is still s390-ccw-virtio-5.0.
The virtual server runs on the earlier hypervisor release and does not exploit the features of the current release.
As long as you do not change the machine type to the new release, a migration of this virtual server back to its original source host will succeed.