[pve-devel] Live migration should check for host compatibility?

[Alexandre DERUMIER]

>>True, host *is* really only useful in single-node clusters,

you shouldn't have difference between "host" vs "haswell" , on a haswell cpu for example.

And maybe some haswell cpuflags not supported by qemu-kvm, are removed from haswell cpu models, to avoid guest problems/crash.



----- Mail original -----
De: "Daniel Hunsaker" <danhunsaker at gmail.com>
À: "aderumier" <aderumier at odiso.com>, "Waschbüsch IT-Services GmbH" <service at waschbuesch.it>
Cc: "pve-devel" <pve-devel at pve.proxmox.com>
Envoyé: Samedi 21 Mars 2015 10:09:37
Objet: Re: [pve-devel] Live migration should check for host compatibility?



True, host *is* really only useful in single-node clusters, or homogenous clusters at worst. It's not intended for production use. I have found it increases performance quite a bit when running Windows 7 in a VM, though. (A highly nonstandard setup for a highly unusual use case. Not recommended for general use.) 
On Sat, Mar 21, 2015, 02:26 Alexandre DERUMIER < aderumier at odiso.com > wrote: 


Hi, 
for proxmox 4.0, we have added a qemu enforce option, which check if cpu flags exist on host machine when vm is starting. 

Of course, this works only if you choose a specific cpu model. 

(In my opinion, "host" should never be used. Only speficic models are safe and well tested) 



----- Mail original ----- 
De: "Waschbüsch IT-Services GmbH" < service at waschbuesch.it > 
À: "pve-devel" < pve-devel at pve.proxmox.com > 
Envoyé: Samedi 21 Mars 2015 07:03:06 
Objet: [pve-devel] Live migration should check for host compatibility? 

Hi all, 

Martin has kindly redirected me to the list as the appropriate place to ask / discuss this: 

I noticed that, even though a kvm guest is set to CPU type 'host', the live migration feature does not check for compatibility with the destination host. 
E.g. Moving from a Opteron 6366 to an Intel Xeon E5420 is going to cause the migrated VM to choke and die due to lots of CPU features no longer being there. 

That in itself is not surprising, but my suggestion would be to at least have a warning popup when choosing to migrate a kvm which is set to CPU type 'host'? 

Best, 

Martin 

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