Re: [Qemu-devel] live migration + licensing issue.

[Markus Armbruster <armbru@redhat.com>]

Eduardo Otubo <eduardo.otubo@profitbricks.com> writes:

> On Fri, Jul 11, 2014 at 1:12 PM, Markus Armbruster <armbru@redhat.com> wrote:
>> [Top-quote moved to its rightful place; please do not top quote on
>> technical lists]
>>
>> Anshul Makkar <anshul.makkar@profitbricks.com> writes:
>>
>>> On Wed, Jul 9, 2014 at 6:25 PM, Andreas Färber <afaerber@suse.de> wrote:
>>>> Am 09.07.2014 13:09, schrieb Anshul Makkar:
>>>>> Thanks. I got the point.
>>>>
>>>> And for the record, the point is that the machine version on the
>>>> destination side needs to match the source side. So, if the default or
>>>> "pc" alias is used in 1.0, which resolves to pc-1.0, then it needs to be
>>>> pc-1.0, not pc-1.2. If an explicit machine name such as pc-0.15 was used
>>>> then that exact machine must be used on the destination as well.
>>
>>> Hi Andreas,
>>>
>>> "the point is that the machine version on the destination side needs
>>> to match the source side". I hope this is just to avoid the licensing
>>> issue. Else, in all other circumstance, we can specify different pc
>>> models while migrating from source to destination.
>>
>> You certainly can specify whatever machine type you want, but if you
>> specify different machine types on source and target of a migration, all
>> bets are off.
>>
>> It could succeed if the stars align the right way.  It could break
>> obviously and immediately, leaving your machine running on the source.
>> It could migrate your machine to the destination successfully, then blow
>> up there right away, or some time later, taking down your machine.  It
>> could migrate successfully, but silently corrupt data.
>>
>> Regardless of how it breaks, you get to keep the pieces.
>
> What you're saying is that there's no way to migrate (live or offline)
> from Qemu 1.0/1.2 to 2.0 in a *safe way* whatever OS I'm running on
> it?

No, what I'm saying is you need to use the same machine type on source
on destination.

If you don't specify one, you get the default.  If you run different
versions of QEMU on source and destination, their default machine type
may differ.

In that case, find the default machine type on the source (-M help shows
it), then start QEMU on the destination with that machine type.