Product Documentation

VM CPU and Memory Allocation

Nov 20, 2012

You can allocate CPU and initial memory resources to the new VM during VM creation. You can change these values after the new VM is installed, if required.

Option Description
Number of vCPUs Enter the number of virtual CPUs (VCPUs) to assign to the new VM.

You can configure up to 8 VCPUs on a VM. The number of physical CPUs available on the server is shown on this page: to ensure you get the best performance out of the new VM, the number of VCPUs you assign to it should not exceed the number of physical CPUs on the server.

This value can be changed later, if needed. See Change VM properties: CPU

Memory Enter the amount of memory you want to allocate to the VM.

The XenServer templates provide typical VM configurations and set reasonable defaults for the memory, based on the type of guest operating system. You should also take into account the following considerations when deciding how much memory you initially allocate to a new VM:

  • The kinds of applications that will run on the VM.
  • Other virtual machines that will be using the same memory resource.
  • Applications that will run on the server alongside the virtual machine.

You can adjust the memory allocation after the new VM is created on the VM's Memory tab, where you can also enable Dynamic Memory Control (DMC) to allow dynamic reallocation of memory between VMs in the same pool. See the Help topics in the Configuring VM memory folder for details.