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What do choose: 1 vCPU with 4 cores or 2 vCPUs with 2 cores?

Posted on 2014-01-24
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When would I choose the one and when the other? Thank you!
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Question by:Xeronimo
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by:Subhashish Laha
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by:alexgreen312
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The only difference is down to licensing as far as I'm aware, if you take SQL2012 (just an example) and you get your licensing you are licensed for standard I think it can use either 1 socket or 4 cores. If you had 4 sockets each with 1 core it wouldn't use all of them.

It also depends on the application, you may find that you get better performance with more sockets and less cores

See here for example

https://blogs.vmware.com/vsphere/2013/10/does-corespersocket-affect-performance.html
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Andrew Hancock (VMware vExpert / EE MVE) earned 125 total points
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if you have specific licensing needs, you would select Cores.

as for performance the same.
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by:Mysidia
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In the vast majority of cases:  2 vCPUs with 1 core, or  1  vCPU with 1 Core.
In most cases, no more than the very top 5% of the virtual machines in an environment should be assigned more than 2 total virtual CPUs, or more than 2 virtual cores.


From the above two options,  4 vCPUs with 1 core, would ordinarily be preferred, as it is immediately obvious how many scheduling threads the VM has been assigned.

The above two are identical, as far the hypervisor is concerned, and the VM with 4 vCPUs with 1 core and  2 vCPUs with 2 Cores would be scheduled identically --- therefore, the performance characteristics would be identical,  Unless the guest operating system or application Detects the difference, and for some unusual reason decides to artificially treat the configurations differently;  it changes what the guest operating system will be told the hardware is, only.

(Software that is licensed for  unlimited Cores but 1 vCPU,  might refuse to run on a second vCPU, for example --- and artificially reduce its performance;    other applications might refuse to start in that scenario.)


The option of specifying multiple "cores" is provided to assist with software that licenses differently based on number of CPU sockets versus cores;  before the option of setting multiple cores on a vCPU, even if your physical server had a single core 8 proc,  all CPUs would be presented to the guest operating system as separate sockets.
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