8.3. Virtualization Hosts

8.3.1. Sizing Guidelines for Oracle VM VirtualBox Servers

8.3.1. Sizing Guidelines for Oracle VM VirtualBox Servers

We found that the 'VMs/core' unit, while being striking, is a fuzzy statement as the available CPUs today differ by at least a factor of 2 in performance and that even ignores older CPUs customers may want to reuse. Therefore we decided to also provide the 'SPEC CINT2006 Rate (peak) / VM' value. Statements made based on this unit are valid for a longer time as they abstract from a concrete CPU, while statements based on 'VMs/core' hold true for cores showing roughly the same performance only.

CINT values for a vast number of CPUs can be looked up from the database of the Standard Performance Evaluation Corporation (SPEC) at http://www.spec.org/cpu2006/results/rint2006.html or by running the provided test suite.

The numbers for this section have been updated based on a new test run. We were able to run 100 VMs on a X4170 with two E5520 CPUs having 4 cores each. The SPEC CINT2006 Rate (peak) for servers with two E5520 CPUs is ~200 which results in a cint / VM value of 2.

  • Number of cores = number of running desktops / 12.5

    Example: A server roughly equivalent to a X4170 with two E5520 CPUs can support up to 2 x 4 x 12.5 = 100 running desktops

  • Memory size [MB] = number of running desktops x memory size of a desktop x 1.2 + 1024 MB

    Example: A server with 64 GB of memory can support 64 x 1024 MB - 1024 MB / (512 MB x 1.2) = 105 running desktops of 512 MB in size

  • Network bandwidth [Mb/s] = storage network bandwidth / number of Oracle VM VirtualBox servers


At least 20% of the available CPU power, memory size and network bandwidth should be available as security margin.