What is the difference between "Total Virtual CPUs", "Cores per Virtual Socket" and "Virtual Sockets" for RHEV Virtual Machines?

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Virtualization 3.1
  • Red Hat Enterprise Virtualization 3.2
  • Red Hat Enterprise Virtualization 3.3
  • Red Hat Enterprise Virtualization 3.4

Issue

  • While creating new virtual machine in Red Hat Enterprise Virtualization, there are some parameters which can be set manually:
  1. Total Virtual CPUs
  2. Cores per Virtual Socket
  3. Virtual Sockets
  • What is the meaning of above parameters?

Resolution

  • Total Virtual CPUs is the total number of vCPUs seen by the VM. If the Number of CPUs on the Hypervisor is 20 then a maximum of 20 vCPUs can be assigned per VM.

  • Under Advanced Parameters -> Cores per Virtual Socket and Virtual Sockets are for customizing how the VM sees these vCPUs. This is designed to allow the VM to comply with third party application licenses.

    • For example, if the application is licensed to run on 2 sockets and you want to use 20 vCPUs then you can customize the above parameters to use 2 virtual sockets with 10 cores each.

  • To be clear, there is no performance impact derived from the configuration of virtual sockets and cores per virtual socket.

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