[libvirt-users] Should domain be undefined after migration, or not?

[Joaquim Barrera]

On 19/01/14 17:03, Brian Candler wrote:
> I have been running a lab using libvirt under Debian Wheezy (libvirt 
> 0.9.12.3-1, qemu-kvm 1.1.2+dfsg-6, virt-manager 0.9.1-4). There are a 
> number of machines as front-end servers and an nbd shared storage 
> backend.
>
> When I live-migrate a domain from one machine to another, normally I 
> observe that afterwards the domain remains on the source host (but in 
> "shutdown" state), as well as on the target host (in "running" state). 
> But occasionally I have observed the domain being removed from the 
> source host.
>
> The trouble with the domain remaining on the source host is that it is 
> all too easy to double-click on the shutdown domain in virt-manager 
> and start it there accidentally, in addition to the copy on the target 
> host - resulting in disaster. (I know this can be prevented using the 
> sanlock plugin)
>
> Furthermore, there could be stale copies of the XML lying around on 
> some machines where the domain had been running at some point in the 
> past.
>
> My question is, what is the expected behaviour? Is not removing the 
> domain definition from the source host a bug? Has this been changed in 
> a newer version of libvirt?
>

Brian, as far as I can tell, when you live migrate a domain you can use 
the flags --undefinesource and --persistent

The first one, as you can guess, will undefine the domain in the source 
host after migration succeeds. The second flag, combined with the first, 
may be the one troubling you. It is meant to leave the migrated domain 
transient in the destination host. That means once you shutdown the VM 
or migrate it, the domain will disappear from the domain list.

Hope this helps you.

> Thanks,
>
> Brian.
>
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