Eduardo Otubo <eduardo.ot...@profitbricks.com> writes: > On Fri, Jul 11, 2014 at 2:19 PM, Markus Armbruster <arm...@redhat.com> wrote: >> Eduardo Otubo <eduardo.ot...@profitbricks.com> writes: >> >>> On Fri, Jul 11, 2014 at 1:12 PM, Markus Armbruster <arm...@redhat.com> >>> wrote: >>>> [Top-quote moved to its rightful place; please do not top quote on >>>> technical lists] >>>> >>>> Anshul Makkar <anshul.mak...@profitbricks.com> writes: >>>> >>>>> On Wed, Jul 9, 2014 at 6:25 PM, Andreas Färber <afaer...@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. >> > > Let me rephrase that: > What you're saying is that there's no way to migrate (live or offline) > from pc-model 1.0/1.2 to pc-model 2.0 in a *safe way* whatever OS I'm > running on it?
Yes, where "migrate offline" is something like savevm / loadvm. The only safe way to upgrade to a newer machine type is shutdown & restart with new type. > As Anshul said, we want to migrate clients of our data center from > Qemu 1.0/1.2 to Qemu 2.0 to take advantage of live vertical scaling -- > which implies in changing pc-model to 2.0. At least offline migration > you think it could be OK? Changing the machine type is the virtual equivalent of replacing the motherboard. No safe way to pull that off without a reboot, I'm afraid.