[virt-tools-list] Live Migration of KVM VMs

[Cole Robinson]

On 06/23/2010 05:45 PM, Phil Meyer wrote:
> We are running RHEL-5.5 hosts.
> All VMs are KVM.
> All VMs have dedicated iscsi targets.  Those targets are made multi-host 
> and enabled on the target host prior to the migration.
> 
> Live migration from virt-manager running on my Fedora 13 desktop, does a 
> live migration, and creates the domain.xml file on the target.  It 
> leaves the domain.xml file on the original host, which needs to be 
> undefined manually.
> 
> PROBLEM:
> Running virsh directly on the command line, does NOT create the 
> domain.xml file on the target host.
> 
> Staring for a while at the python scripts in the virt-manager source 
> brought no inspiration.
> 
> Here is the command line used on my Fedora 13 desktop:
> 
> $ virsh -c qemu+ssh://root@172.20.1.1/system migrate --live --persistent 
> --undefinesource 7659-centos-core qemu+ssh://root@172.20.1.16/system
> 
> Both of those hosts are RHEL-5.5
> 
> The version of virsh/libvirt on those hosts do not support --persistent 
> or --undefinesource.
> 
> However, virt-manager seems to get --persistent to work or at least 
> emulates that function somehow when communicating with hosts that have 
> older versions of libvirt.
> 
> How does it do it?
> 

It does it by basically running

virsh dumpxml $vmname > foo.xml
virsh --connect DESTINATION_URI define foo.xml

after the migration has completed. --persistent is just a convenience
option for those commands.

- Cole