Problem: Windows In A VirtualMachine On UCS Does Not Start


A Windows virtual machine does not start properly after being powered on through UVMM. The remote screen of the virtual machine might show some Windows symbols but Windows hangs forever.


You have not configured a specific CPU model for this VM. By default a “Pentium Core2 Duo CPU” is shown to the virtual machine. Windows starting from version 7 get confused about such an old CPU and can not start.


Configure a CPU model from within UVMM or use the passthrough mode.
When using “host-model” the virtualisation layer will configure the virtual machine (VM) to always use the current CPU even when being migrated to a host with different (newer) CPU.
Using “host-passthrough” offers the VM the current available physical CPU on the virtualisation host.
Univention recommends to use “host-model”.

For environments where you perform live migrations you should take care of the following UCR variable:

root@ucs:~# ucr search host-model
uvmm/vm/cpu/host-model: <empty>
 For live migration of virtual machines UVMM can track the exact CPU model of the host systems. Setting this variable to 'missing' will insert such a description only if it is missing. 'always' will also overwrite any previous setting. 'remove' will delete an existing description; any other value (including unset) will not change the description, which is the default.