[libvirt-users] Deploying libvirt with live migration

[Matthias Bolte]

2010/12/13 David Ehle <ehle at agni.phys.iit.edu>:
>
>
> On Mon, 13 Dec 2010, Matthias Bolte wrote:
>
>> 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.
>
> Thank you for explaining that - I usually use the gui admin tool so some of
> the details I'm oblivious too.
>>
>>> 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.
>
> I think that would be more than sufficient ;)
>
> Is that project publicly accesible?  I might be interested in lending a hand
> :)

Search the libvir-list (not the libvirt-users one) for "lock manager"
or "sync manager". This threads here are probably be a good starting
point to read about it:

https://www.redhat.com/archives/libvir-list/2010-August/msg00179.html
https://www.redhat.com/archives/libvir-list/2010-September/msg00167.html

Matthias

> David.
>>
>> 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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>>>>
>>>
>>
>