[PVE-User] Cluster mixed hardware behavior (CPUs)

Thomas Lamprecht t.lamprecht at proxmox.com
Fri Apr 26 17:13:11 CEST 2019


Am 4/26/19 um 4:56 PM schrieb Roland @web.de:
>> will run at the lowest common denominator. In other words, if you have 3
>> hosts each with CPU frequencies being 2.1 GHz, 2.3 GHz, and 2.5 GHz
>> respectively, the entire cluster will run at a 2.1 GHz level.
> 
> huh, really? never heard of that, where is that information from?
> 
> from what i know, clustering is about cpu features, not speed, see
> https://communities.vmware.com/thread/545610
> 
> What vmware does is EVC ( https://kb.vmware.com/s/article/1003212 ) ,
> that way you can mask what cpu features/instructions should be used
> within the cluster.
> 
> my proxmox knowledge is limited, but from what i can see you set what
> cpu features being used at VM level (hardware ->processors ->type)

exactly, and the default "kvm64" is a CPU type with reduced registers
so that, in theory, you can live migrate between all 64 bit amd64/x68_64
based host CPUs. You may still get into issues if you mix vendors (AMD,
Intel) but between same vendors you normally really won't have issues.

(also the inter-vendor may work, but they make far more often troubles,
it seems)

cheers,
Thomas

> 
> roland
> 
> 
> 
> 
> Am 26.04.19 um 14:05 schrieb Craig Jones:
>> Hello,
>>
>> To my understanding, in the vSphere world, a cluster with hosts of mixed
>> CPU frequencies and generations (let's assume consistent manufacturer)
>> will run at the lowest common denominator. In other words, if you have 3
>> hosts each with CPU frequencies being 2.1 GHz, 2.3 GHz, and 2.5 GHz
>> respectively, the entire cluster will run at a 2.1 GHz level. Is this
>> the same in the Proxmox world or what would be the equivalent behavior
>> for a Proxmox cluster?
>>
>> Thanks,
>> Craig
>>
>>
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