Re: KVM in HA active/active + fault-tolerant configuration

[g.danti@assyoma.it]

On 2013-08-22 02:35, Timon Wang wrote:
> On Thu, Aug 22, 2013 at 5:47 AM, Brian Jackson <iggy@theiggy.com> 
> wrote:
>> On Wednesday, August 21, 2013 3:49:09 PM CDT, g.danti@assyoma.it 
>> wrote:
>>> 
>>> On 2013-08-21 21:40, Brian Jackson wrote:
>>>> 
>>>> On Wednesday, August 21, 2013 6:02:31 AM CDT, g.danti@assyoma.it 
>>>> wrote:
>>>> ...
>>> 
>>> 
>>> Hi Brian,
>>> thank you for your reply.
>>> 
>>> As I googled extensively without finding anything, I was prepared to 
>>> a
>>> similar response.
>>> 
>>> Anyway, from what I understand, Qemu already use a similar approach
>>> (tracking dirty memory pages) when live migrating virtual machines 
>>> to
>>> another host.
>>> 
>>> So what is missing is the "glue code" between Qemu and KVM/libvirt 
>>> stack,
>>> right?
>> 
>> 
>> Live migration isn't what you asked about (at least not from what I
>> understood). Live migration is just moving a VM from one host to 
>> another.
>> That is definitely supported by libvirt. Having a constantly running
>> lock-step sync of guest state is what Qemu/KVM does not support. So 
>> with
>> Qemu's current live migration abilities, if HostA dies, all it's 
>> guests will
>> have downtime while they are restarted on other hosts.
>> 
>> 
> 
> Live migration is not proper for support VM HA, when host went wrong,
> these VMs on the host must be restart on another host based on the
> same storage.
> 
> I have googled for KVM FT for a while, but only find a project called
> Kemari which was no longer updated.
> I read some article about KVM FT, which said KVM may be support it in 
> future.
> 
> 

Yes, I understand that live migration is not proper to VM HA/FT, but 
the basic working principles (track and copy dirty pages) is already at 
work in live migration. I was thinking to something along what Zheng 
suggested ("hot backup" with very frequent/continuous memory 
synchronization from a "master" guest).

I totally overlooked Kemari, glad to see that someone point me to it. 
Shame that is dead (at the moment).

Thanks you all guys.

>>> 
>>> Thanks again.
>>> 
>>>>  ...
>>> 
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe kvm" in
>>> the body of a message to majordomo@vger.kernelorg
>>> 
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>> 
>>> 
>> 
>> --
>> To unsubscribe from this list: send the line "unsubscribe kvm" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html