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From ilya <ilya.mailing.li...@gmail.com>
Subject Re: Intel v3 and v4 CPUs in the same cluster
Date Fri, 10 Feb 2017 19:07:19 GMT
https://media.readthedocs.org/pdf/cloudstack-installation/4.8/cloudstack-installation.pdf

Page 76 explains it.. you want for CPU instructions sets to match and be
consistent if you plan to run v3 and v4 cpus in the same cluster.

Regards
ilya

On 2/10/17 8:23 AM, Rafael Weingärtner wrote:
> From my experience, yes it would work.
> 
> At the end what matter are the CPU capabilities, meaning the instructions
> tha can be used by operating systems (O.S) and their processes, in this
> case, VMs can be considered processes in the hypervisor (hypervisors are
> OS). We normally do the masking to hide features that may only be available
> in one host or other; when you migrate a VM of a host (without masking), if
> the VM ends up in a host that does not have the same CPU features it may
> crash or present unexpected behaviors.
> 
> On Fri, Feb 10, 2017 at 11:15 AM, Nando Beifiori <nandobeifiori@gmail.com>
> wrote:
> 
>> Hi Rafael,
>>
>> in this case the hypervisor is KVM and I think it supports masking, but let
>> me check if I got it right:
>>
>> if the CPU is not exactly the same the features can be masked using
>> hypervisor's capabilities.
>>
>> Does it mean that if the CPU has the exact same features but different
>> frequency for example it would work?
>>
>> Thanks
>>
>> On 10 February 2017 at 15:46, Rafael Weingärtner <
>> rafaelweingartner@gmail.com> wrote:
>>
>>> It depends on your hypervisor.
>>> For XenServer, you should check the CPU feature you have and if the CPU
>>> supports masking [1].
>>>
>>> xe host-cpu-info
>>>>
>>>
>>> Look for the "features" information, and then check if your hardware guy
>>> can provide a processor with similar features or one that supports
>> masking
>>> the same features as your current servers' CPUs.
>>>
>>> [1] https://support.citrix.com/article/CTX127059
>>>
>>> On Fri, Feb 10, 2017 at 10:28 AM, Nando Beifiori <
>> nandobeifiori@gmail.com>
>>> wrote:
>>>
>>>> Hi all,
>>>>
>>>> quick but very important question: I have a cluster with Intel Xeon
>>> E5-2667
>>>> v3 CPUs and I need to add another host, but my provider has replaced
>> the
>>> v3
>>>> with the v4 of the same CPU.
>>>>
>>>> The differences are:
>>>>
>>>>    - Lithography (22nm > 14nm)
>>>>    - Cache size (20MB > 25MB)
>>>>    - Max Memory Bandwidth (68 GB/s > 76.8 GB/s)
>>>>    - Intel TSX-NI feature which is present in v4 but not in the v3.
>>>>
>>>> Frequency, turbo frequency and cores are exactly the same.
>>>> Would it be possible to add the new host to the same cluster or should
>> I
>>>> create a new cluster or maybe look for a provider that still has the v3
>>>> CPU?
>>>>
>>>> Cloudstack version is 4.9 and hosts use Centos 7.2.
>>>>
>>>> Thanks in advance
>>>>
>>>
>>>
>>>
>>> --
>>> Rafael Weingärtner
>>>
>>
> 
> 
> 

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