[libvirt-users] Deploying libvirt with live migration

[Matthias Bolte]

2010/12/13 David Ehle <ehle at agni.phys.iit.edu>:
>
> Even if your not sharing /etc/libvirt, if you have migrated at least once,
> both systems see the VM's as available for starting/running so just not
> sharing /etc/libvirt is not a solution to the problem/concern...

Well, that depends on the flags you pass to the migrate command. The
default libvirt migration semantic is a bit unexpected as it leaves
the domain defined but in shutdown state on the source host and on the
destination host it's running as a transient guest. That's why I gave
it the --persistent --undefinesource flags to make it take it's config
with it.

> Ideally if you try to start a VM that is already running on a different host
> it should balk and you should get an (overridable) warning. (IMHO)

There is ongoing work on a lock manager system for libvirt that shall
prevent two domains from using the same disk image at the same time.
That's not exactly what you're looking for but it's related.

Matthias

> David.
>
> On Mon, 13 Dec 2010, Scott Baker wrote:
>
>> On 12/13/2010 02:28 PM, Matthias Bolte wrote:
>>>
>>> Well don't share /etc/libvirt, there is no need to.
>>>
>>> Just have the domain config on the host that currently executes the
>>> domain and tell libvirt to migrate the persistent domain condif along
>>> with the domain:
>>>
>>> virsh migrate --persistent --undefinesource vm1 qemu://virt2/system
>>
>> I suppose that would work... but if Virt2 dies and I need to start its VMs
>> on Virt1 those XML configs won't be there and it will make it more
>> complicated.
>>
>> Not just a simple "virsh start Foobar"
>>
>> --
>> Scott Baker - Canby Telcom
>> System Administrator - RHCE - 503.266.8253
>>
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>